Homemade Baking Powder

1 teaspoonful baking soda
2 teaspoonsful cream of tartar
1 teaspoonful cornstarch (optional)

Whisk baking soda and cream of tartar together. If adding cornstarch, whisk it together with the previous two ingredients.

Use immediately or store in an air-tight container. If you plan to store homemade baking powder, you need to add the cornstarch to absorb moisture. Makes one tablespoonful.