Why I think tempeh is fascinating

Tempeh is a fascinating product. I regularly make it at home, and I always find it so surprising that from completely tasteless beans you can create such delicious food. A good tempeh has a nutty taste, and sometimes notes of mushrooms. While the ingredients you start with have no taste at all.

The origin of tempeh can be found in Indonesia, or more specifically Java. It is believed that the first tempeh was made by packing black soybeans into hibiscus leaves. The mold on the hibiscus leaves made the beans get into a cake, that can be baked or cooked any other ways. Later, when Java became a production hub for tofu, the white soybeans grown for tofu were also used for tempeh.

While a lot of tofu was produced on Java for China, it looks like tempeh stayed a local dish in Indonesia until the 20th century. This probably had to do with the fact that it was really food for poor people, it was not eaten by the noble families, and therefore wasn't written about it a lot. Still I think it is surprising that China, with so many great products made of soy never adopted tempeh. At least not on a large scale.

Nowadays most tempeh is produced from white soybeans, using rhizopus oryzae as a starter to get the mold growing. This starter (in small bags, mixed with rice flour) can be purchased online is shops specialising in fermentation.

I have been making tempeh at home for quite some time. It is fairly easy as long as you have a spot to maintain a constant temperature of 30 degrees Celsius for 48 hours. This can be done in a special device, but if you have an oven that can go that low, you can use that. Only thing is you won't be able to use the oven for preparing food for the 48 hours you need to keep it at 30 degrees.

I have tried making tempeh with other beans and grains (white beans, chickpeas, special local beans, buckwheat) but so far soybeans produced the best tasting tempeh. Which is surprising, as these are the most tasteless beans of all. You can buy hulled soy beans. If the beans are not hulled, you should try to remove the skins of a quarter of the beans after soaking and before cooking. With all the skins on the mold might not grow strong enough.

To make tempeh I soak the beans overnight, and then cook them. They do not need to be completely done, so cooking for 30–45 minutes is fine. Some people add a little vinegar to the cooking water to make sure there are no unwanted molds, however I have also made tempeh without the vinegar, and never got into trouble.

After cooking you need to cool down the beans to approximately 35 degrees Celsius before adding the tempeh starter. On about 500 grams of dried beans a teaspoon of starter will do. So you really need only a little bit of starter to get things going.

Then you can either put the beans into ziplock bags (and punch around 20 little holes with a wooden skewer in every bag to get some oxygen in) or do the beans in petri dishes with a glass lid. That's what I prefer, especially because the tempeh gets a nice, round shape. And the lid of the petri dish seems to give just enough oxygen for the process.

Now put them in the oven or other warm place for about 48 hours. They are ready when all beans are tied together with a white mold, and you hardly see a trace of the beans. You might see some black spores, this is no problem, these are the spores of the rhizopus oryzae. If you see any blue, green or bright yellow spores, there might be something wrong.

When ready you can use them immediately (fresh it tastes best), keep them in the fridge for a few days, or put them in the freezer for later use.

Preparing tempeh is easy. Most recipes tell you to marinate it and then bake or deep fry it. In Indonesia it is often marinated in coriander powder, garlic and turmeric. And deepfrying is the standard. I prefer to bake it until golden brown, and only then add a marinade of soysauce or kecap with spices. Adding the marinade after baking improves both the taste and the structure of the tempeh.

Recently there has been more attention for tempeh. More restaurants are putting it on the menu. With it's high level of protein (comparable to chicken) and low level of fat it's a healthy (not ultra-processed) meat replacement. And although I really appreciate tempeh getting more popular, let's hope it doesn't get into a 'superfood' hype.