Shred or julienne the carrot and thinly slice the onion and pepper. Mince the garlic (unless you’re using garlic paste) and thinly slice the spring onion and set aside.
Rinse the spinach and lightly brush the mushrooms clean.
Step 2: Prepare the noodles
Soak the noodles in boiling water for 3 minutes before draining and rinsing them in cold water (or placing them in an ice bath). Feel free to use some kitchen scissors to slightly cut up the noodles too (before or after soaking).The time will vary based on the noodles you use – be careful not to overcook the noodles, though, as slightly firmer noodles are easier to stir-fry.
Step 3: Stir fry the vegetables
In a large skillet, heat the cooking oil of medium-high heat, then add the sliced onion and garlic and cook for 1-2 minutes.
Add the carrot, shiitake, and red peppers and stir fry for a further 2-3 minutes.
Reduce the heat to medium and add the spinach, cooking until it wilts, stirring often.
Step 4: Add the noodles
Add the noodles, soy sauce, sesame oil, sugar, and a pinch of salt, and stir to incorporate. Cook for a further minute to allow the sugar to dissolve properly, then finally add the spring onion and gently stir to mix.
The veggie japchae is ready to serve! Optionally sprinkle with some sesame seeds and chili threads.
How to Store
Make ahead: vegetable japchae can be enjoyed cold, at room temperature, or warm – so preparing it the night before works fine.Fridge: allow the noodles to cool, then transfer to an airtight container and store in the refrigerator for between 2-3 days.Reheat: use a microwave or the stovetop to reheat the Korean glass noodles until warm throughout.Note that the japchae noodles will harden and generally become more opaque when cold. However, they will soften up again when reheated.
Cook the elements separately: traditional japchae cooks each of the ingredients separately before combining them with the noodles, and this is meant to yield better overall flavor and texture. I usually add the ingredients incrementally based on their differing cooking times (to save time). However, feel free to cook the vegetables and noodles separately then mix them when serving.
Using dried shiitake: make sure to soak the shiitake mushrooms for several hours before using them. You can also save the soaking liquid for broths and stocks.
Be careful not to overcook the vegetables: they should still be slightly crunchy for texture and freshness. Make sure to add the vegetables in at different times according to their cooking times.
Optional add-ins and variations
Vegetables: feel free to add in other vegetables based on what you have in your fried. Good options include zucchini, Bok choy, broccoli, peas, cabbage, etc.
Proteins: to create more of a meal, feel free to add in some crispy tofu or the protein of your choice.
Egg: you can add a fried egg as a garnish or beat the egg whites and yolk separately, then fry them up and thinly slice them before mixing them into the prepared vegetable japchae.
Sesame seeds: raw or lightly toasted sesame seeds work well as a garnish.