Homemade tempeh

For a long time I wanted to try making tempeh, but I was put off because it sounded too hard. First, the whole process of splitting and getting the hulls off the soybeans seemed like a big hassle. And second, it seemed like you would need an incubation chamber to keep the fermenting tempeh at a stable warm temperature. But reading Sandor Katz' The Art of Fermentation convinced me that it was totally doable.

I bought my starter culture from Indopal.

I decided to skip the whole issue of splitting and hulling soybeans by using split hulled broad beans (fava beans) instead. I begin by soaking 460g of beans for 24 hours (the long soak at a warmish temperature allows them to start fermenting -- according to Katz this step probably creates a good environment for the tempeh mold to grow in).

The next step is to partially cook the beans. You definitely want to under-cook them: they need to be firm so that they don't mush together. Firm beans allow space between them for the tempeh mold to grow. I simmered these beans for about 12 minutes; they were firm but some were starting to get feathery on the edges.

Next, you let the beans cool to body temperature. It's important that they are dry -- with a batch this size it works well to tip the beans onto a towel and dry them. Then you put them into a bowl and stir through the starter thoroughly (the amount might depend on your particular starter -- mine calls for 1 tsp).

For the next step, you put the beans into sandwich bags, which you have poked some air holes into with the point of a knife. For this batch, I used 4 10x15cm bags. You should smush the beans down so that they fill the bags all the way to the corners.

I like to do all of this in the morning, on a day when I will be around to keep an eye on the incubation. For the first 12 hours, the tempeh needs to incubate at about 28 degrees. Luckily or unluckily for me, in the summer time in my house that's about room temperature, so I don't need an incubation chamber. After about 12 hours, the tempeh mold should have started growing and creating its own warmth. If you were using a heat source to incubate the tempeh, this would be the time to turn it off or down, and this is why I like starting in the morning: the cooler night time temperature arrives at the right time for the tempeh.

(When it's cooler, I've had success using my Excalibur dehydrator as a heat source. I run the dehydrator at its lowest temperature (85F) and put the tempeh on racks on top of the dehydrator, and then cover the whole lot with an overturned bowl to keep the warmth in. I check the temperature every so often, and turn the dehydrator off if it's getting too warm.)

After 24 hours, tempeh: