Sweet Potato Burger With Portobello Mushroom Bun

5 from 14 votes
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A healthy yet indulgent fully-loaded sweet potato burger with rainbow veggies, and a portobello mushroom bun. Slice your veggies thick for a towering masterpiece to impress or thin for a burger that still impresses in taste and looks. This recipe is nutrient-dense, vegetarian, low saturated-fat, with a gluten-free & low-carb bun alternative, and can be made vegan by omitting the fried egg! 

Portobello mushroom bun burger with veggies and sweet potato patty

This fully-loaded portobello mushroom burger bun is stacked high with a combination of rainbow veggies and sweet potato and white bean burger to impress friends and family. In fact, I first came up with this recipe as a delicious (yet simple to make) surprise for Father’s Day – but it works for any day of the week. And don’t be worried about the tower of veg I’ve included in my images – slices your veggies and thin or thick as you want to impact how tall your burgers become. 

By packing this burger with rainbow veggies, it means that it’s also packed with nutrients – who says you can’t have a healthy burger? Definitely not me, for sure. This sweet potato veggie burger combines lettuce, avocado, red onion, rainbow tomatoes, peppers, all topped with an (optional) fried egg, and packed into a portobello burger bun. 

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The Ingredients

For the Burger buns and filling

Ingredients for Mushroom 'bun' burger

An example of some of the rainbow vegetables that you could add into this burger.

  • Portobello mushrooms – Try to choose mushrooms that are a similar size and large enough to hold the width of your widest veggies as the mushroom caps will be used as the burger bun.
  • Lettuce leaves – You can also use spinach or whatever salad leaves that you like. 
  • Tomatoes – I chose to use red and yellow tomatoes for the rainbow effect. Feel free to use a single variety of tomato.
  • Bell Peppers – I used a combination of orange and red raw bell peppers for crunch, flavor, and color. However, you could also grill the peppers for a smoky flavor and softer texture.
  • Red onion – If you don’t like the harsh flavor of raw onion then feel free to fry it lightly or allow the onion to sit in some lemon juice or vinegar for a few minutes and it will help mute that harsh raw flavor.
  • Avocado – No burger is complete without avocado in my opinion. You can thinly slice, make into a quick mash (which is easier to assemble) with lemon or lime juice, or even use this Simple Fresh Authentic Guacamole (Mexican).
  • Coconut oil, for pan or olive oil/ your oil of choice for the frying.
  • Egg (optional) – I used Clarence Court Burford Brown Egg for their rich yolk. Feel free to omit this for a vegan recipe.

Note: You can use your own rainbow veggies of choice, like the suggestion above. For a super simple version, I suggest using lettuce, avocado, and tomato. 

For the Sweet Potato Patties

Mixing sweet potato with spices and flour

These ingredients make around 4 patties. Any leftovers can be formed into patties and frozen.

  • 1-2 large Sweet potato, baked (may need two potatoes if you’re looking for thicker patties)
  • Cannellini beans, drained – You could also use black beans for a traditional sweet potato black bean burger.
  • Chopped spinach
  • Tahini – I use homemade 
  • Apple cider vinegar
  • Garlic, onion, cayenne (for heat), smoked paprika, black pepper – feel free to omit the cayenne if you don’t like spice and mix up the herbs and spices, if preferred.
  • Salt & pepper
  • Oat or wheat flour – Use oat flour if you want a gluten-free option
  • Panko bread crumbs for crispy ‘breading’ – Make sure to use gluten-free breadcrumbs, if preferred. 

The Step By Step Instructions

Step 1. Prepare the sweet potato burger patties

Begin by baking and peeling the sweet potatoes. You can bake the sweet potatoes in the oven if preferred but I like to speed this process up with a microwave. Simply prod the sweet potato a few times with a fork and wrap in a damp (but not dripping) paper towel. Microwave for 3 minutes then turn over and repeat. 

Check the potato is fully cooked by piercing with a knife. If it needs slightly longer then microwave for a further minute, as needed. 

Allow the potatoes to cool slightly (just enough to handle comfortably) and scoop out the flesh from the skin. 

Add the beans and baked sweet potato to a bowl and mash. 

Mixing sweet potato with spices and flour

Then add the chopped spinach, tahini, a splash of vinegar, and mix.

Mixing sweet potato with spices and flour

Add in all the seasonings and the flour – if the mixture is still too wet then thicken with a little extra flour. Sweet potatoes can contain different levels of moisture, which is why this can vary. 

Mixing sweet potato with spices and flour

Divide the mixture into four and form into patty shapes. Dip each sweet potato cake into panko breadcrumbs for a super crispy coating.

Mushroom 'bun' burger patties

At this point, preheat the oven to 200°C/400ºF.

To cook the patties, first heat 1/2 tbsp of oil in a frying pan and cook over medium heat until lightly browned on each side (just 2-3 minutes per side). If you have a pan large enough to fit multiple at one time, even better!

Mushroom 'bun' burger

To finish the cooking place in the oven for 12-15 minutes until warmed through.

Mushroom 'bun' burger

Step 2. Prepare the Fillings

While the burgers are cooking in the oven you can prepare all of the fillings. Chop the vegetables as thick or as thin as you’d like. Use a mandoline for nice and thin, evenly sliced pieces. If using carrots then you can use a vegetable peeler to cut it into strips. 

If you prefer to saute any of the vegetables, simply heat in the same frying pan that you cooked the sweet potato burgers in for a few minutes, until lightly sauteed. You can also lightly charr the peppers over a flame/under the grill in the oven. 

Mushroom 'bun' burger

Step 3. Prepare the Portobello Mushroom buns

Simply remove the mushroom stalks and brush the outside of the portobello mushroom caps with a little oil, salt & pepper (add a dash of soy sauce or GF tamari for a little extra flavor). To cook the portobello bun, you can either fry them lightly on each side for a few minutes or simply place the mushroom caps in the oven at the same time at the patties. 

Note* The mushrooms may shrink in size in the oven and release water so aren’t as crispy as the pan-fried version. 

Portobello mushrooms

When there are just a few minutes left of the cooking time then you can, optionally, fry an egg to top each burger. 

Portobello mushroom bun burger with veggies and sweet potato patty

Step 4. Assemble the burger

Stack the burger bun with all your rainbow veggies, the patty, and fried egg. For a little heat, you can top with a sprinkle of Red Pepper Flakes.

Portobello mushroom bun burger with veggies and sweet potato patty

How To Store

Once prepared, the uncooked sweet potato burger patties can be frozen for between 1-2 months. Simply place the patties (not touching) layered in a freezer-safe container, separated by layers of parchment paper or beeswax wrap and freeze. To use, simply allow to thaw in the fridge and then cook in the oven.

You can also freeze the cooked patties. However, this isn’t something I’ve done before so I’m not sure how this affects the shelf life. 

How To Serve

Serve these burgers alone or wish side dishes such as:

A side salad: such as this Simple Fatteh (Pita with Herby Chickpeas and Yogurt)Traditional Tabbouleh Salad (Tabouli Salad)Simple Traditional Lebanese Fattoush Salad, or Simple quinoa salad with walnuts and avocado.

Other Side dishes: Such as  Crispy Baked FriesLebanese Spicy Potatoes Batata Harra, or Easy Potato Salad With Egg (Mashed Potato Salad)

Condiments: No burger would be complete without your favorite condiments. Feel free to use Mayonnaise, Ketchup, or Mustard

Recipe Notes

  • I like a slightly chunkier texture so mash the patties with a fork. However, feel free to use a food processor if you’d prefer. 
  • You can use whatever favorite veggies that you’d like. You can also include burger favorites like these Homemade Easy Pickled Cucumbers
  • If you’re on a keto or paleo diet, you can use the portobello burger bun and veggies then simply omit the sweet potato patty in place of a keto/paleo-friendly burger patty.
  • You may also like these natural squid ink black burger buns.
  • Tomatoes – I chose to use red and yellow tomatoes for the rainbow effect. Feel free to use a single variety of tomato.
  • Bell Peppers – I used a combination of orange and red raw bell peppers for crunch, flavor, and color. However, you could also grill the peppers for a smoky flavor and softer texture.
  • Red onion – If you don’t like the harsh flavor of raw onion then feel free to fry it lightly or allow the onion to sit in some lemon juice or vinegar for a few minutes and it will help mute that harsh raw flavor.
  • Avocado – No burger is complete without avocado in my opinion. You can thinly slice, make into a quick mash (which Is easier to assemble) with lemon or lime juice, or even use this Simple Fresh Authentic Guacamole (Mexican).

If you give this rainbow veg and sweet potato burger recipe a go, then let me know your thoughts in the comments. Also, feel free to tag me in your recreations @AlphaFoodie.

Sweet Potato Burger With Portobello Mushroom Bun

5 from 14 votes
By: Samira
A healthier yet still decadent mushroom bun burger with a sweet potato and white bean patty and fully-loaded rainbow vegetables. This recipe is vegetarian though can easily be made vegan and gluten-free!
Prep Time: 20 minutes
Cook Time: 25 minutes
Total Time: 45 minutes
Servings: 4 burgers

Ingredients 
 

 For the patties (makes 4 patties):

  • 1-2 Large sweet potato baked (may need two potatoes if you’re looking for thicker patties)
  • ½ can Cannellini beans drained
  • ½ cup chopped spinach
  • 1 tbsp tahini I used homemade
  • Splash of apple cider vinegar I used homemade
  • ¼ tsp garlic powder, onion powder, cayenne, and black pepper remove cayenne for a heat-free version
  • Additional seasonings – to taste salt & pepper
  • 1/6 cup oat or wheat flour oat for GF
  • Panko bread crumbs for crispy ‘breading’ or GF bread crumbs

For the buns and filling – Use the rainbow vegetables of your choice – the below are all suggestions!

  • 2 Portobello mushrooms try choose evenly sized ones large enough for the vegetable and patty width
  • 2 handfuls lettuce / salad leaves
  • 1 beef tomato or tomato of your choice
  • 1 Orange/red peppers raw , charred, or baked.
  • 1 egg omit for vegan option
  • ½ Red onion
  • 2 Avocadoes
  • 1-2 tbsp Coconut oil for pan

Instructions 

Step 1. Prepare the sweet potato burger patties

  • Begin by baking and peeling the sweet potatoes. You can bake the sweet potatoes in the oven if preferred but I like to speed this process up with a microwave. Simply prod the sweet potato a few times with a fork and wrap in a damp (but not dripping) paper towel. Microwave for 3 minutes then turn over and repeat.
    Check the potato is fully cooked by piercing with a knife. If it needs slightly longer then microwave for a further minute, as needed.
  • Allow the potatoes to cool slightly (just enough to handle comfortably) and scoop out the flesh from the skin.
  • Add the beans and baked sweet potato to a bowl and mash. Then add the chopped spinach, tahini, a splash of vinegar, and mix.
  • Finally, Add in all the seasonings and the flour – if the mixture is still too wet then thicken with a little extra flour. Sweet potatoes can contain different levels of moisture, which is why this can vary.
  • Divide the mixture into four and form into patty shapes. Dip each sweet potato cake into panko breadcrumbs for a super crispy coating.
  • At this point, preheat the oven to 200°C/400ºF.
  • To Cook the patties, first heat 1/2 tbsp of oil in a frying pan and cook over medium heat until lightly browned on each side (just 2-3 minutes per side). If you have a pan large enough to fit multiple at one time, even better!
    To finish the cooking place in the oven for 12-15 minutes until warmed through.

Step 2. Prepare the Fillings

  • While the burgers are cooking in the oven you can prepare all of the fillings. Chop the vegetables as thick or as thin as you’d like. Use a mandoline for nice and thin, evenly sliced pieces. If using carrots then you can use a vegetable peeler to cut it into strips.
  • If you prefer to saute any of the vegetables, simply heat in the same frying pan that you cooked the sweet potato burgers in for a few minutes, until lightly sauteed. You can also lightly charr the peppers over a flame/ under the grill in the oven.

Step 3. Prepare the Portobello Mushroom buns

  • Simply remove the mushroom stalks and brush the outside of the portobello mushroom caps with a little oil, salt & pepper (add a dash of soy sauce or GF tamari for a little extra flavor). To cook the portobello bun, you can either fry them lightly on each side for a few minutes or simply place the mushroom caps in the oven at the same time at the patties.
    Note* The mushrooms may shrink in size in the oven and release water so aren't as crispy as the pan-fried version.
  • When there are just a few minutes left of the cooking time then you can, optionally, fry an egg to top each burger.

Step 4. Assemble the burger

  • Stack the burger bun with all your rainbow veggies, the patty, and fried egg. For a little heat, you can top with a sprinkle of Red Pepper Flakes.

How To Store

  • Once prepared, the uncooked sweet potato burger patties can be frozen for between 1-2 months. Simply place the patties (not touching) layered in a freezer-safe container, separated by layers of parchment paper or beeswax wrap and freeze. To use, simply allow to thaw in the fridge and then cook in the oven.
  • You can also freeze the cooked patties. However, this isn’t something I’ve done before so I’m not sure how this affects the shelf life.

Notes

  • I like a slightly chunkier texture so mash the patties with a fork. However, feel free to use a food processor if you’d prefer. 
  • You can use whatever favorite veggies that you’d like. You can also include burger favorites like these Homemade Easy Pickled Cucumbers
  • If you’re on a keto or paleo diet you can use the portobello burger bun and veggies then simply omit the sweet potato patty in place of a keto/paleo-friendly burger patty.
Ingredient Notes:
  • Tomatoes – I chose to use red and yellow tomatoes for the rainbow effect. Feel free to use a single variety of tomato.
  • Bell Peppers – I used a combination of orange and red bell peppers for crunch, flavor, and color. However, you could also grill the peppers for a smoky flavor and softer texture.
  • Red onion – If you don’t like the harsh flavor of raw onion then feel free to fry it lightly or allow the onion to sit in some lemon juice or vinegar for a few minutes and it will help mute that harsh raw flavor.
  • Avocado – No burger is complete without avocado in my opinion. You can thinly slice, make into a quick mash (which Is easier to assemble) with lemon or lime juice, or even use this Simple Fresh Authentic Guacamole (Mexican).
Course: Main
Cuisine: American
Freezer friendly: 3 Months (uncooked)
Shelf life: 1 Day

Nutrition

Serving: 1burger, Calories: 137kcal, Carbohydrates: 23g, Protein: 5g, Fat: 3g, Saturated Fat: 1g, Cholesterol: 41mg, Sodium: 60mg, Potassium: 618mg, Fiber: 4g, Sugar: 6g, Vitamin A: 9135IU, Vitamin C: 15mg, Calcium: 44mg, Iron: 1mg

Nutrition information is automatically calculated, so should only be used as an approximation.

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2 Comments

  1. MiTmite9 says:

    Came here to say that Panko bread crumbs are NOT gluten-free. So, if you’re like me and steering clear of gluten —— make your own bread crumbs using the heels from your $$$ gluten-free bread loaves. (I store heels of bread in my freeze so I can make my own bread crumbs just for these types of recipes.)

    1. Support @ Alphafoodie says:

      Thank you for your feedback.