Step 1: Soak the soybeans (If you haven't already)
Soak the beans for at least 8 hours, or overnight then drain and rinse well.The leftover soaking water can be used to water plants but shouldn't be used for human consumption.
Step 2: Cook the beans
Add the soybeans to a large pot with enough water to cover them by around an inch above the beans. Bring the mixture to a boil over medium heat, skimming any foam as needed.
Lower the heat, cover with a lid and simmer for around 35-40 minutes - until the beans are almost ready (about 80%).
Add the vinegar, and cook for a further 10-15 minutes.You can add the vinegar at the start of the cooking process for a more infused flavor. However, the cooking process is slowed down and will take longer than I've mentioned.This process may take slightly less/longer for you, so check their done-ness after this time and increase if needed. The soybeans should be tender without being mushy.'
Sieve the cooked beans and allow them to cool slightly. Place them back in the pot in which they cooked so that the heat from the pot dries them out as they cool down. If you have a thermometer, you want them to cool to around 95ºF/35ºC.
Add the tempeh starter and mix well to coat all the beans.
Step 3: Place the beans in the banana leaf
Cut the leaf to the required size (enough to fold over without too much excess).
Scoop portions of the soybeans into the leaves' center and wrap them into small, tight parcels, securing them with a few toothpicks.You can change the tempeh's shape and depth based on personal preference; I usually make mine in a similar rectangular shape as a block of tofu (but obviously not as 'thick - refer to the images on the blog post). Depending on how tightly you wrap the leaf with change the thickness of the loaf.You can do a similar process in perforated ziplock bags, folding the bag over to squeeze the beans into your thickness of choice. Alternatively, you can place the beans in a large glass container, fill it about halfway, and then place its lid on. Keep in mind that, if using a glass container, the tempeh will be less compact and a large layer of spores will develop on top of the beans.
Step 4: Ferment the homemade tempeh
Move the parcels to a warm location (or incubator) to allow for the fermentation. This can be done in an oven with the light on (remove after 12 hrs and leave in another ventilated warm area, possibly covered with a teatowel for warmth if needed), a warm cupboard, etc. Just make sure there is airflow.Top Tip: The mycelium grows best at temperatures between 85-90ºF/29-32ºC. So, just like you would when leaving bread to rice, it's best to incubate the fermenting soybeans somewhere warm, optionally using a thermometer.If you're using an external heat source, this usually is no longer needed after 12 hours, as the beans will now be producing their own heat from the fermentation process. You then need a ventilated warm area.
Within 26-48 hours, the mycelium should have grown and covered all of the beans. If not, leave for up to another day. Then, the tempeh is ready to be sliced, stored, or prepared and cooked for your recipes.A little bit of grey/black on the mycelium is fine - but if the beans start to smell or turn completely black, then something has gone wrong during the fermentation process.
How To Store
Fridge: You can store the tempeh in the refrigerator for up to a week.Freezer: Freeze the tempeh, covered well, for up to 6 months. I freeze mine raw and then steam/boil it from frozen. It can also be pre-steamed before freezing.
To substitute the soybeans for another the process will stay the same except for how long you need to boil the legume.
You can use the leftover soy pulp (called "okara") from making homemade soy milk to make tempeh, too- with a couple of tweaks. Reduce the vinegar amount to 1/3 and heat the mixture to 90ºF/35ºC. Then combine with the starter and carry on with the method above.
Please do NOT season the tempeh in any way before the fermentation, or it may interfere with the mold growth.
The main reason that tempeh fails is due to too much moisture in the process; either the beans being too wet when the process was started (just before adding the starter), or the way you've incubated the beans has led to condensation. This is why it's important to have airflow and not allow the beans to become too hot.
If you're using a thermometer during the fermentation process, make sure to insert it directly into the beans for an accurate reading.
A few tiny grey or black marks on the tempeh is fine - it's actually the same type of mold, just "older".
Check the blog post for more helpful tips and answers to top FAQs!