Begin by washing the lime(s) thoroughly. Usually, when the juice alone is needed, nothing more than a quick rinse is required, but if you will be using the zest, which is directly on the surface of the lime, you will need to make sure it is completely clean, and free of any dirt, or debris. Once you have washed it, remove any leaves or twigs, and pat the lime dry.
Now, there are two methods you can use to grate your lime, and these depend on the sort of zest you are looking for. Keep in mind that the zest is the thin, green layer on top of the lime. Directly below it is the white part of the peel, also known as the pith – when zesting, it is necessary to take off just the zest, and avoid removing the pith along with it, as the pith has a bitter, unpleasant flavour.
If you are looking for curls of zest which you wish to use for making candied lime peel, or for using as drink garnishes, you will need to use a vegetable peeler for the zesting. Hold the lime firmly in your hand, and hold the vegetable peeler in the other hand. Working carefully and precisely, start peeling just the zest off the top of the fruit, and without pausing, move downward, peeling around the fruit in a spiral. Be firm, but do not dig into the pith.
Once you have removed all of the peel in this manner, lay the broad strips of zest onto a cutting board, and using a paring knife, cut these into strips that are as narrow or wide as you desire. These strips can be used to garnish drink glasses, and in cakes or curries, etc.
However, if you are looking for zest that is in powder form, you will need to use a sharp metal grater with small holes. Simply hold the grater firmly in one hand, and run the surface of the lime across it until the zest is dislodged – however, do not keep grating just one area, otherwise you will start removing the pith too. Continue grating all over the lime, until you have the amount of zest you need.