Add a little zest.
When a recipe calls for a “zest” of a citrus fruit, it’s referring to the
colorful outer part of the skin, not the inner white part, which is known as the
pith. The zest contains all of the aromatic citrus oils and provides a hint of
citrus tang to the recipe. A simple method of obtaining a fine zest is by
rubbing the fruit against the smallest holes of a cheese grater.