The prickly pear cactus grows in many parts of the world, and its large egg-shaped berry--a pinkish- or yellowish-brown fruit covered with spines--is popular in Mexico and the American Southwest, all over the Mediterranean, in South Africa, and in Israel (whose natives are nicknamed "sabras" for their supposed resemblance to cactus fruit: prickly on the outside and sweet on the inside). You can eat the melony-flavored fruit by itself, or use it in fruit salads or drinks.
Choose cactus pears that are soft but not mushy; let them ripen at room temperature for a few days if they are warm when you buy them, then refrigerate.
To eat the juicy flesh, which is full of seeds (edible in some types, too hard to chew in others), you have to get past the prickly skin. Wear rubber gloves, use tongs, or hold the fruit impaled on a fork to protect yourself, then cut off the ends of the fruit, slit it lengthwise in several places, and peel the skin off.