The most common, and of course the simplest option, is to buy ready-to-cook cacti. But sometimes they are only sold unpeeled, so you need to be able to remove the thorns. Get a sharp knife and to begin with, cut the thorns off at the base (the white part, where the leaf meets the plant). Then, place the cactus at an angle and cut horizontally. By doing this you cut through the base where all the thorns grow from. Finally cut around the outer edges of the cactus, because these thorns are the hardest to remove.