Long popular in Mexico, these fleshy oval leaves (also called pads or paddles) of the nopal (prickly pear) cactus are gaining popularity in the United States. They range in color from pale to dark green and have a delicate, slightly tart green-bean flavor. Though fresh nopales (also called cactus leaves) are available year-round in Mexican markets and some supermarkets, they're at their most tender and juicy best in the spring. Look for small, firm, pale-green nopales with no sign of wrinkling. Refrigerate tightly wrapped for up to a week. Before use, the thorns must be removed; a vegetable peeler will shave them off quickly. The flesh is generally cut into small pieces or strips, simmered in water until tender and used in a variety of dishes from scrambled eggs to salads. Nopalitos (nopales that are diced or cut into strips) are available canned (pickled or packed in water). Acitrónes are candied nopales, packed in sugar syrup and available in cans or jars.