Place the dried in a colander or mesh sieve and rinse under cold water. This removes any dust or debris from the dried beans.
Place the drained beans in a medium bowl. Add enough boiling water to the bowl to cover the beans by ½ inch (1.25 cm). Let stand for 20 minutes until the beans are slightly plumped and the water has cooled.
Drain and rinse the beans in a mesh sieve or colander, discarding the soaking water.
Place the drained beans, 2 and ¾ cups tap water and optional salt in a blender. Blend on high speed until completely smooth, stopping several times to scrape down the sides of the blender container.
Pour the bean mixture into a medium-size, heavy-bottomed saucepan.
Whisk over medium-high heat for 6 to 8 minutes until the mixture is VERY THICK, glossy and begins to pull away from the sides of the pan as you whisk.
Scrape the batter into an 8-inch (20 cm) square glass or ceramic baking dish, smoothing the top.
Refrigerate the tofu, uncovered, for at least 8 hours, or overnight.
Run a silicone spatula or dull knife around the edge of the dish; invert the tofu onto a cutting board. Cut the tofu into the desired shapes and sizes you prefer for recipes and/or storing in the refrigerator.
