Distressed by the chemical additives and aftertaste of commercial “double-acting” powders, Miss Lewis years ago started making her own baking powder—a traditional mixture of cream of tartar and baking soda. When I first used her formula (from her books, before we met), I couldn’t really taste any difference. Soon, though, I realized that muffins and quick breads made with aluminum-sulfate–based powders left a metallic “tingle” on my tongue. Today, I make up a batch of this powder every week for use at the restaurant and bring a jar home for Miss Lewis. We recommend it for all the recipes here. If necessary, you can substitute commercial baking powder in equal amounts.