The lactose intolerant, or those who avoid animal products on ethical grounds, can consume one of the many plant-based alternatives to dairy milk. One of the most widely available is soy milk, which is made by grinding whole soybeans and steeping them in water. At home, it's simpler to make soy milk from already-processed soy flour. Whole-fat soy flour produces a beverage similar to whole milk, while defatted soy flour produces the equivalent of fat-free milk. Defatted soy flour is sometimes sold as "soy milk powder," which positions it as a convenience product similar to instant powdered milk.
Measure out a cup of defatted soy flour. Add it to 4 cups of cold water and mix them thoroughly. Use an immersion-style "stick" blender or a conventional blender.
Refrigerate the mixture immediately. Let it infuse for at least 4 hours before drinking, so the water can fully extract soluble solids from the soy flour.
Pour the soy milk though a colander or mesh strainer lined with several layers of cheesecloth, taking care to disturb it as little as possible while you pour. Leave behind the bottom half-inch of soy milk, which will contain much of the sediment. This step is optional, but it helps minimize the "chalky" texture that mars homemade soy milk.