Zest: The perfumy outermost skin layer of citrus fruit (usually oranges or
lemons), which is removed with the aid of a Citrus Zester, paring knife or
Vegetable Peeler. Only the colored portion of the skin (and not the white
pith) is considered the zest. The aromatic oils in citrus zest are what
add so much flavor to food. Zest can be used to flavor raw or cooked
and sweet or savory dishes.