Rinse black soybeans thoroughly and soak them for at least 8 hours.
Boil the soaked black soybeans in boiling water for 20 minutes.
Remove the skins from the boiled black soybeans.
Put the black soybeans and water into a blender and blend until smooth to make soy milk.
Strain the soy milk for a smoother texture.
Add a pinch of salt to taste and serve.