Soak 1 cup dried soybeans in plenty of water for 8–12 hours
Drain and rinse the soaked soybeans
Remove the skins by rubbing the beans gently in water, then skim off the loose skins
Rinse the beans again
Blend the soybeans with 4–5 cups of fresh water until smooth
Pour the blended mixture into a large pot
Cook over medium heat, stirring often to prevent sticking and boiling over
Simmer for 15–20 minutes
Turn off the heat and let it cool slightly
Strain the mixture through a cheesecloth, nut milk bag, or fine sieve
Squeeze or press to extract as much liquid as possible
Discard or save the leftover soy pulp
Add sugar, salt, or flavoring if desired
Chill and store in the refrigerator
Shake before using