The intense flavor and aroma of citrus zest adds great flavor to so many foods from soup to sauces to cookies and cakes. The real trick in using lemon, lime or orange zest is to remove only the outer, colored layer of the peel. Avoid the bitter white pith underneath. Scrub the citrus well with a vegetable brush or coarse sponge to clean off any dirt or markings. Next grate the zest, using a zester or the smallest holes on a conventional box grater. You can also slice the zest off with a sharp paring knife or vegetable peeler and then finely mince it.