79 2/3 g  Potassium Bicarbonate
56 g  Cornstarch
15 g  Tartaric Acid
112 1/4 g  Potassium Bitartrate

Combine all ingredients in a bowl, mix well. Store in an airtight
container. Use 1 1/2 teaspoons of sodium free baking powder for each
teaspoon of regular baking powder.