What are you making and what role do the nuts play? Whole nuts and fragments are most often used in recipes just to add flavor, and can generally be omitted. Some people substitute soy nuts - which are not nuts, but roasted soybeans - to add flavor and crunch when nuts are off limits. Soy nuts are available salted or unsalted, and can be found in health food stores if not your local supermarket.

If a recipe calls for a flour-like nut ingredient such as almond meal, the substitution of flour may be your best bet. But some people prefer to use bran instead, which imparts much more flavor.

In the case of a nut butter or puree, the nuts add flavor, oil, and solids to the recipe. In that case, you might consider adding some flour or bran to substitute for the solids and some oil to replace the fat. You may have to guess at what the texture of the dough or batter would be if you used the specified ingredients, and experiment with the quantities of flour and oil needed to approximate the right texture.