A few years ago, I learned how to make tempeh at Sandor Katz‘s fermentation workshop in middle Tennessee. After seeing the process, it seemed like a lot of work, and I admit that I did not want to rush out and try it. But I’m glad I finally took the plunge!

What is tempeh?

Tempeh is an Indonesian bean cake, made by culturing (or more precisely inoculating) a legume, traditionally soybeans, but most any bean will work, with Rhizopus oligosporus fungus spores, then incubating for 24 to 36 hours at tropical temperatures (85°-90°F/29°-32°C). Here’s where I get my tempeh starter. [Disclosure: I am an affiliate of CFH and receive a small commission for sales of their products.] The fungus will propagate itself in and amongst the substrate (the medium on which the fungus grows and feeds– the beans and rice), consuming some of the protein in the beans, and taking the form of the container in which the tempeh is incubating.

What you do with it is up to you! Many people treat it like tofu– try marinating it in some soy sauce, rice vinegar, oil and chili paste for a half-hour before frying in some coconut oil. If you have an interesting recipe, please share it in the comments section!

Which legumes are best to use for making tempeh?

Soybeans are the most common legume used to make tempeh. However, according to William Shurtleff in his wonderful The Book of Tempeh, beans with a high protein and low starch content (chickpeas/garbanzos, pink beans, pinto beans, red kidney beans, California blackeye-pea, or black beans) work best. Beans with high carbohydrates (mung, azuki, lentils), says Shurtleff, become mushy after cooking, and in my experience, they hold onto moisture. Having the right moisture level to make tempeh is critical; “Wetter” beans are not as ideal. The Rhizopus mycelium needs nooks and crannies in the substrate which to grow. If you’ve got more of a “muddy” field (i.e. with a softer, wet cooked bean), then the mold hyphae can’t get a good foothold!

Other Interesting Facts

Making tempeh is the same process by which mushrooms are cultivated. But most cultivated mushroom species we are familiar with (crimini, oyster, enoki) grow at cooler temperatures. And with mushrooms, we eat the fruiting portion of the fungus (the “above-ground” part) rather than the mycelium (the body, which with mushrooms is usually underground). With tempeh, we eat the mycelium and the substrate and do not wait for it to fruit. In fact, it doesn’t “fruit” like other mushrooms; rather it sporulates (creates spores) on its surface, giving it a black, blue or green splotchy look.

Note that tempeh is not a “lacto-fermented” food like sauerkraut or yogurt, meaning that there are no lactic acid bacteria or probiotic properties after you have prepared it. The “fermentation” refers to the process of propagating the culture (fungus) in the incubator. But there are many other benefits to eating tempeh, including beneficial enzymes, and the fact that the beans are more easily digestible (and nutrient-accessible) compared to uncultured, cooked beans.

Batch #1: Chickpeas + Oven + zip-top bags

FIRST TIME: I followed the basic recipe from Sandor’s Wild Fermentation book, but also paid attention to the instructions from the starter culture I got from Cultures for Health, and took a few tips from Sandor’s new book, The Art of Fermentation. Note that tempeh is a cultured ferment, meaning that you need to add a specific culture to create it. (It will not spontaneously form the way that, say, sauerkraut would.)

INCUBATOR: If you live in an area where the room temperature is between 85° and 90°F, then you don’t need an incubator. Room temperature around these parts is about 70°F and relative humidity 45%, so I needed to simulate the tropics. I put a $12 clamp lamp with a 40W incandescent bulb to generate heat at the bottom of my oven. If you have a pilot light or a bright oven light, often that will generate enough heat. I added a shallow pan of water to increase humidity.

You can also build a custom fermentation curing chamber!

I used chickpeas (aka garbanzo beans), which I had soaked for 24 hours in whey and water. I also mixed in some “dry-cooked” brown rice (another Sando-vation) into the substrate to absorb some of the residual moisture from the cooked beans.

The recipes call for hulling the beans (removing the skins) so that the mold can more easily get to the proteins. Being lazy, I didn’t bother with this step, although I did mash the beans and removed many of the hulls manually.

I kept the temperature between 87° and 91°F/30° and 32°C degrees throughout the incubation. It actually took closer to 48 hours for the fungus to fully bloom. Once dark grey/black spots form (indicating the fruiting phase), I knew it was ready and I removed it from the “heat.”

Finally, I removed it from the bags and let it cool to room temperature before refrigerating. I sliced it all and fried some right up! If you are not going to eat all of it within a few days, freeze the remainder. Slicing it before freezing lets you make a little at a time.

Batch #2: Dehydrator + banana leaves

DEHYDRATOR: This device is a good tempeh-maker! Even the most budget versions have a temperature control. Set it sucker to 95°F and fuggedahboudit! It’s brilliant at keeping air circulation and temperature constant throughout the process, making it a perfect tool for the job.

Banana leaves were originally used, and are common tools in southeast Asian cooking. For our second time, we went old-school after finding some beautiful banana leaves locally.

Second pass, we tried aduzki beans and barley as our substrate. It was a bit wetter than we wanted (barley is highly absorbent), so it took 55 hours in the dehydrator to fully develop. We suspect that if we started with a drier mixture, we can get that time down by at least 12 hours.

We learned not to mash the beans too much, as that creates a denser and wetter mixture. We want the substrate to be light enough to allow the mycelium to form. That requires cracks, crevices and crannies, so keep the beans as whole as possible.

Batch #1 Gallery

Batch #2 Gallery

Batch #3 Gallery