Baking powder

Use 25% of the baking powder's weight (e.g. 1 g for 4 g) and add 2 g cream of tartar or 1 tsp lime juice per 100 g flour. Mix quickly and bake at once.

Same as baking soda: use 25% of the weight with an acid such as cream of tartar, lemon juice or yogurt. Expect a slightly soapy taste if overused.

Replace the plain flour plus baking powder with the same weight of self-raising flour; omit added baking powder and reduce salt slightly.