Milling grain into flour requires specialized equipment, but nut flours are more obliging. All that's required is a small investment of time, and a few items you probably already have in your kitchen. Whether you view them as a protein-rich addition to your standard recipes, or as a gluten-free substitute for conventional flour, making your own at home is the simple path to freshness and quality.
Wash raw almonds, macadamia nuts, hazelnuts, walnuts, chestnuts or other nuts in hot water to remove any loose soil, shell fragments or other debris.
Fill a medium saucepan half full with cold water. Bring the water to a rolling boil over high heat on the stove top.
Add the nuts to the water, then bring it back to a full rolling boil. Boil the nuts for 10 seconds, then drain them in a colander.
Pour the nuts onto a clean towel. Fold the towel over the nuts and rub them vigorously to remove their skins. Scoop the peeled nuts from the towel, and peel away any remaining skins with a fingernail or paring knife.
Toss 1/2 to 1 cup of the peeled nuts into a nut grinder; do not overfill the grinder. If you don't have a nut grinder, use your blender and grind no more than 1/2 cup of nuts at a time. Pulse the nuts carefully, until they break apart and reach the texture of coarse breadcrumbs. If you grind them too long, they'll turn into nut butter instead.
Place a sifter over a mixing bowl and slowly shake the nut flour through the mesh. Pour the remaining large pieces back into the nut grinder along with your next batch of intact nuts. Repeat as needed, until the nuts are all ground.
Almond flour has a neutral, slightly sweet flavor that makes it the most versatile of nut flours. For other nut flours, match the nut's own flavor with complementary foods. For example, hazelnuts have a noted affinity with chocolate while pistachios' woodsy flavor lends an interesting note to chicken or veal.
Store the nuts in your freezer, in an airtight container or plastic zip-top bag, for up to a month. Once ground, the nut flour rapidly becomes rancid at room temperature.