Rinse and drain the soybeans, pick out the bad ones and then soak it in cold water for 8 - 16 hours. Make sure the water level is at least 2"(5cm) above the soybeans.
Blend and cook the soy milk
Drain the soaked soybeans and blend it with 6 cups of water in a blender over medium to medium high speed for 1-2 minutes. I use the 4-5 speed setting with my Vitamix.
In a 5-6 qt pot, bring 1 cup of water to a boil before pouring the soy milk mixture into the pot. Use 1 cup of water to rinse the blender and pour it into the pot.
Bring the soy milk to a boil, reduce the heat to a simmer and continue to cook for another 15 minutes. Stir occasionally and skim off foam from the top.
Let the soy milk cool down a little before pouring soy milk into a mixing bowl through a nut milk bag.
Once it's cool enough to handle, squeeze out as much of the soy milk in the nut milk bag as you can. Optionally sweeten with sugar.