1. Put chicken fat and skin, onions, salt, and 3⁄4 cup water into a 12" skillet over medium-low heat. Cook, stirring, until fat has rendered and skin is crisp, about 1 1⁄2 hours. Strain, reserving crisp skin to use as a garnish for sautéed greens or chopped liver. Schmaltz will keep, in a tightly sealed container in the refrigerator, for 2 weeks.