Soak the soybeans overnight. Drain and grind in a blender (add about 3 cups of water while grinding)

Strain soybeans through a cheese cloth or sieve.Pour the sieved milk into a big Pot, Boil the soy-milk on medium heat for 45 minutes to 1 hour, stirring frequently (be careful, the milk has a tendency to over boil).
Reduce the heat, add in lime juice (do not stir), tofu will start to form. Turn off the heat, cover the pot, set aside for 1 hour.

Place the cheeseclothor sieve in a bowl or over the sink, pour the tofu in carefully, fold the cheesecloth over and press out as much soy milk water as possible(this is to remove all excess water from the tofu and allow it to set).when set ie became hard tofu is ready.