Bean Flour: Any dry bean can be ground into flour using a hand or electric mill. Read your instructions carefully, some specifically say you cannot use beans in them.
• Bean flour can be whisked into boiling water and seasonings to make an almost instant soup or thickener. [Some kinds of raw beans and especially red and kidney beans, contain a harmful toxin (the lectin Phytohaemagglutinin) that must be destroyed by cooking. A recommended method is to boil the beans for at least ten minutes.]
• Bean flour can be used in any recipe calling for flour by replacing up to 25% of the wheat flour with any variety of bean flour (instead of 2 cups wheat flour, use ½ cup bean flour and 1 ½ cups wheat flour). The bean flour combined with the wheat flour creates a complete protein.
•White beans or fava beans have a milder taste, making white bean flour or fava bean flour suitable for use in most recipes calling for white flour. Substitute 1/4 of the white flour for bean flour.
•Bean flour made from kidney, pinto, garbanzo, chana dal or black beans has a stronger flavor and is more suitable for inclusion in meat loaf or when making vegetable patties or vegetarian loaves.
•Bean flour can be whisked into soups and stews, adding flavor and goodness. Bean flour can also be used to thicken these dishes.
Here's more information regarding Phytohaemagglutinin on Wikipedia and Your Dictionary.
Here are a couple of articles on bean flour from Emergency Essential and Suite101.
• Method 1: Mashed white beans replace fat cup for cup in recipes. Mash until consistency of shortening (use blender). Replace in recipes cup for cup. (Example: Recipe calls for 1 cups margarine, use 1 cup mashed beans.) Liquid may be added to adjust the consistency. Mashed beans do not keep long in the fridge, so freeze them.
• Method 2: Grind beans in your wheat grinder. Store in air-tight container. Replace fat in the recipe cup for cup. You will need to add more liquid since the ground beans will be part of the dry ingredients.