- 2 cups hulled soy beans (if using beans with the hulls intact, see below for extra steps)
- 2 tablespoons vinegar
- 3/4 teaspoon (1 packet) tempeh starter
- Boil the soybeans for 1 hour to cook.
- Discard the cooking water and dry the beans (either using a towel to pat them dry or setting over low heat in the pot to evaporate the water off the beans). It is important for the beans to be dry to the touch, as too much moisture can ruin the batch.
- Place the beans in a dry bowl and allow the beans to cool to a lukewarm temperature (same temperature as your skin).
- Add the vinegar and mix well.
- Add the tempeh starter and mix well to evenly distribute the starter in the beans.
- Place the beans in two vented containers (or quart-size plastic bags with needle-size holes poked through at 1/2-inch intervals). The beans should be 1 to 1-1/2 inches thick.
- Incubate the beans at 88°F for 24 to 48 hours. See below for ideas for incubating the beans.
- Check the beans after 12 hours. At this point in the process the fermentation will cause the beans to generate their own heat so you will normally need to reduce or even eliminate the external heat source. Be sure to use a thermometer to check the actual temperature (see below).
- After 24 hours or so, the white mycelium will start to cover the surface of the beans. Over the next few hours the white mycelium will grow through the beans and will smell nutty.
- After 24 to 48 hours, when the beans have become a single mass held together by the white spores, the tempeh can be refrigerated.
Tips for Making Tempeh
- It's not unusual for there to be a bit of a learning curve when making tempeh. If your first batch doesn't turn out, just try again.
- Use a thermometer to verify the ongoing temperature of the tempeh during fermentation. (A meat thermometer with an alarm often sold for baking and for the BBQ are very useful as they will warn you if the temperature falls outside a set range.)
- If you wish to freeze the finished tempeh, steam the tempeh over boiling water for 20 minutes to cook then slice into patties and soak overnight in salt water (2 teaspoons salt to one pint water). The patties can then be patted dried and frozen for future use.
Incubation Methods (Heat Sources) for Making Tempeh
Proper temperature is vital for the fermentation process. While a temperature range of 85° to 91ºF is technically acceptable, ideally the tempeh should ferment at 86° to 88ºF. Regardless of which method you choose to keep your tempeh warm during the process, be sure to verify that the method you are using will achieve and maintain the proper temperature and check the temperature often during the process. Here are a few possible methods for maintaining the proper temperature:
- Large cube-shaped dehydrator (i.e., Excalibur or TSM Dehydrator).
- Oven with a low temperature setting or with just the light turned on. (Check the temperature of your oven first as ovens vary in heat.)
- Cupboard with a low-level heat source (like a high-wattage light bulb).
- Styrofoam or plastic "cooler" with warm water bottles to maintain the heat.
- Low-temperature mat such as those sold for reptiles (pet store) or to maintain sprout seedlings (gardening store). Please note, these mats generally keep the tempeh about 10 degrees above the ambient temperature so they will still require a rather warm room. This is not the same as a commercial heating pad which normally runs far too warm for this purpose.
- Incubate outside if you live in a warm climate.
- A warm part of your home during the summer months (e.g., a non-climate controlled attic, etc.).
Removing Soybean Hulls
The easiest way to make tempeh is to use de-hulled soybeans, but if they are not available you will need to remove the hulls prior to making tempeh.
- Soften the soy beans either by soaking or boiling:
- Soak the beans in 6 cups of water for 6 to 18 hours OR
- Boil the beans for 15 minutes, turn off the heat, and allow the beans to sit for two hours
- Separate the hulls from the soy beans:
- Split the beans by squeezing them with a kneading motion. The hulls will float on the water and can be skimmed off. OR
- Remove the beans from the water and place in a shallow baking dish. Use a potato masher to split the beans and loosen the hulls. Add the beans and hulls back to the water so the beans will sink and the hulls will float. The hulls can then be skimmed off. You may need to repeat this process several times to remove all the hulls and it can take approximately 10 minutes.
- Boil the now hulled beans for 30+ minutes until they are cooked through. (You can then skip the alternative cooking process in the above recipe and proceed directly to drying the beans.)