Zest is the outermost colored part of the rind of a lemon, lime, orange, or other citrus fruit. When the zest is removed, none of the bitter white pith underneath should be attached. The citrus oil in the zest is what infuses a dish with an intense citrus flavor. You can use a zester to remove the zest in thin strips for garnishing; chop the strips if you want to add the zest during cooking. A swivel-bladed vegetable peeler removes the zest in long, wide strips. Cut the strips into julienne or chop fine and add to the dish, or toss whole strips into soups or other cooking broths and remove before serving.