Nopal is a general name for several kinds of cactus with edible paddles and fruit. Various species of the Opuntia genus grow wild in different regions, especially central Mexico. There are also cultivated nopales. The mild-flavored cactus paddles or pencas (the youngest, tenderest, fleshy “leaves”) are commonly used as a vegetable. They are covered with thorns, sometimes hard to see, which must be cut out with a knife (gloves must be worn when handling them). Before cooking they are usually cut into strips and simmered briefly in water with a small amount of baking soda or tequesquite to reduce their mucilaginous—well, frankly, slimy—quality. If you don’t like okra, which has a very similar quality, you may not like nopales much. Once cooked, they should be rinsed, first in hot and then in cold water, to remove any still-oozing juice. Cooks in Mexico strain them through a heavy straw basket to drain off the juice; here you can rinse them in a colander. They can then be used as a salad, in a stew, with scrambled eggs (substituting them for the string beans in Ejotes con Huevo), or with a sauce like Salsa de Chile Colorado. The whole pencas (unblanched) can also be grilled on a griddle, though be forewarned that they can be slimy. Sliced nopales, dethorned and cooked, are sold in cans in Latin American markets, but I don’t like them much.