2 1-quart zipper bags or 4 1/2-quart zipper bagssee notes
Instructions
SOAKING:
I got my tempeh starter from Cultures of Health and one packet is good for 2 cups of soy beans and so that's the amount I used.
Place 2 cups of soy beans in a large pot. Pour cold water to cover the beans. Let it sit for at least 10 hours or up to 24 hours
DEHULLING:
Drain off the water and fill with more fresh water and use your two hands to rub the soybeans as if you are washing your hands. This will rub off the skin off the soy beans. The skin will rise to the top of the water and scoop those skins away and pour off the water and fill up with fresh water and rub again. Do this for about 3-4 times, or until you take off most of the skin. You may not be able to take off all the skin, but take off as much as you can, but there's no need to be obsessed about it
IF COOKING SOYBEANS ON THE STOVE:
Place the dehulled beans back to the pot and fill up with 8 cups of water, bring to a boil and then lower the heat and cover the pot and cook for 1 hour. Just check on the water to make sure it doesn't run out while you are boiling it. Drain off the cooking water after the beans are soft and cooked through. Proceed to "dry the beans" step below
IF COOKING SOYBEANS WITH PRESSURE COOKER:
Place the dehulled beans in the inner pot of Instant Pot. Fill up with 6 cups of water. Close the lid and turn the steam release valve to "sealing". Press "pressure cooker" and make sure it's on "high pressure". Set timer to 15 minutes and then wait 5 minutes before fully releasing the pressure
Drain off the water. The soybeans should be soft and cooked through, but not mushy. Proceed to "dry the beans" step below
PREPARE BAGS AND CONTAINER TO CULTURE THE BEANS:
While the beans are cooking, you can prepare two 1 quart-size zip lock bags or four 1/2 quart-size zip lock bags that are already poked with a toothpick on both sides (1-inch apart)
DRY THE BEANS:
Spread two to three dry clean absorbent cloth on the kitchen counter or wherever with enough space. Spread the cooked beans on the cloth and use another dry towel to gently rub the beans to dry it. The beans need to be dry to touch. You can also use a hair dryer on low heat to blow dry it. The temperature of the beans should be about 90-95 degrees.
MIX BEANS, STARTER, AND VINEGAR & FILL THE BAGS:
Place the dried soybeans but still slightly warmed beans in a large bowl. Pour in 2 Tbsp of distilled white vinegar and sprinkle 1 packet (about 1 tsp) of the tempeh starter. Use a clean spatula to mix it around to make sure the beans are covered with the starter and vinegar
Fill the bags with the beans, making sure you fill it to the corner but do not overpack it. It should be about 1 to 1 1/2-inches in thickness. Push all air out and seal the bags
IF YOU INCUBATE THE BEANS IN INSTANT POT :
Put a trivet in the inner pot of Instant Pot. Gently put the bags on top of the trivet. Close the lid and press "Yogurt" button repeatedly until the light shows "less" mode and then set the timer to 14 hours. I set to 14 hours first to remind me to check on the beans and wipe off any condensation inside the lid & then continue to culture until about 48 hours using yogurt function
IF YOU INCUBATE THE BEANS IN THE OVEN:
If your oven has a "bread proof" function, turn it on. This helps to maintain the temperature at 90-95 F. If your oven doesn't have this function, turn the oven's light on. This helps to maintain that temperature too. Place the bags of beans on a clean baking sheet and place them inside the oven. Place a thermometer inside the oven so you know the temperature
MONITOR THE GROWTH:
I only start seeing a bit of growth starting at about 24-hour mark in my case when I use an oven as an incubator. The ones in Instant Pot starting to show some growth at around 20 hours. They started to grow rapidly after 24 hours. You will notice that the tempeh culture actually generates its own heat. This process may take up to 48 hours or it may not
The tempeh is done when it covers with white spores all over and you can pick it up like a block without it breaking apart. It should be firm
When you open the lid of Instant Pot to monitor the growth, use a clean paper towel to wipe off the condensation that accumulates on the lid before closing it back again, this way the water droplets won't drop on the tempeh
If you see some black spots, DO NOT PANIC. It doesn't mean that your tempeh is bad. The tempeh should has nutty pleasant fermented aroma. If it smells foul, then the tempeh is most likely no good and you should discard it
The whole process may take up to 48 hours or a bit longer sometimes for fully cultured tempeh
HOW TO STORE TEMPEH:
Wrap them with a plastic wrap. Freeze them if you are not going to cook them anytime soon. It's good up to 6 months in the freezer and about 10 days in the refrigerator
Video
Notes
If you don't want to use a plastic bag, you can use a container or banana leaves. In Indonesia, tempeh is made by piling the soybeans on top of banana leaves and then wrap like a parcel to let it ferments