Soak the beans overnight (about 16hours). Drain and rinse with fresh water and dehull the beans by massaging them into the water until the hulls float up. Then pour them out and repeat. Dehull as many beans as possible. This step will be worth it as it will give you a really smooth and creamier consistency.
Cook the beans in 400g of water for about 20min. It should be cooked but still crunchy. Once the tempeh is done you will be cooking it again, so you want to make sure that it doesn't turn too soft.
Drain the water and let it completely cool down.
Add the tempeh starter and mix until well cooperated.
Place the beans in 2 plastic bags about 12cm x 20cm (5"x8"). Using a toothpick or a skewer poke holes through the bag with 2cm (1-inch) intervals. The beans should be layered about 2cm (1-inch) thick. Divide the beans between the two bags. Seal the bags and flatten the beans out evenly. Leave the beans at a surrounding with a temperature between 25°- 30° (85-90 Fahrenheit) for 36 to 48 hours.
After 24 hours, the white mycelium will start to cover the surface of the beans. You may want to lower the heat source because the beans will start generating their own heat as the mold grows.
After 24 to 48 hours, the tempeh should smell pleasantly nutty. The tempeh is done when the entire surface is covered with dense, white mycelium and is bound together firmly as a cake.
Transfer the tempeh cakes to airtight bags or containers and store them in the refrigerator for up to 1 week.
You could also make a bigger batch and freeze your tempeh for up to 3 months. Only make sure to steam your tempeh for 20min, let it cool down, wrap it in a container or plastic bag before placing it in the freezer.