Wash the chickpeas and black soybeans thoroughly.
Soak the beans in water for at least 8 hours.
Put the soaked beans in a pot and boil until very soft.
Remove the skins from the boiled beans.
Place the cooked beans and water in a blender and blend until smooth.
Strain the blended mixture through a fine sieve.
Pour the strained soy milk into a pot and simmer over medium heat, stirring.
Add a pinch of salt to taste, if desired.
Once fully cooked, turn off the heat and let cool. Ready to serve.