Although you can make your own soy milk, I usually start with a generic store brand that contains as few additional ingredients as possible (some use apple juice or other sweeteners, which is a no-no for good tofu). The only other thing you need is a coagulant, epsom salt works if you don't have any nigari (available online). Anyway, here are the steps I used:
- Start heating one container (one liter) of soy milk in a pan.
- While the soy milk is coming to temperature, put 2-3 tablespoons of warm soy milk in a ramekin or small bowl and dissolve 1 tablespoon marmite per liter of soy milk.
- Stir the dissolved marmite into the rest of the soy milk.
- When the mixture reaches about 180 degrees Fahrenheit or about 75 degrees Celsius, take it off the heat.
- Introduce the coagulant (nigari or epsom salt) and let the soy milk sit covered for 10-15 minutes
- While the soy milk is cooling, prepare the strainer that will remove the excess water from the curds. I use a small tofu press, but you can also line a sieve or steamer insert with cheese cloth.
- Pour the curdled soy milk slowly into the strainer or tofu press.
- When all the curds have been added, fold the cheesecloth over the top of the curds.
- If you're using a tofu press, you should have a lid that goes over the top of the wrapped curds. If you're using a sieve or steamer insert, you'll have to improvise something using a plate or pan or anything that's slightly smaller than the strainer.
- If you want anything beyond soft tofu, you'll need to apply weight to the lid, a pot full of water should be adequate.
- Let the water press out of the tofu in proportion to how firm you like it. For extra firm tofu, leave 15-20 pounds on top of the curds for an hour. For softer tofu, use smaller weight and/or decrease the time.
- When the tofu is at the desired firmness, you can use it immediately or store in water for up to seven days before using.
My recipe is based on my own experience, the instructions for my tofu press, and on a few other recipes I've read online: