Beans (frijoles) are a part of everyday eating, and many beans are grown among the cornstalks of Mexico. The south has black beans, and the north favors pinto beans, but there are many varieties to choose from. (A bean-cooking tip: don`t salt the water when you cook dried beans, as it will make the skins tough). Other vegetables that make Mexican cooking distinctive include plantains, avocados, jicama (a tuber with a sweet, apple-like taste when served raw), cactus paddles (or nopales, fleshy oval lea ves of the nopal -- prickly pear -- cactus), tomatillos (which resemble small green tomatoes with papery husks), tomatoes (both green and red), chickpeas, onions (of course), purple skinned garlic, wild mushrooms, and chayote (a native squash). Citrus fruits such as the citron, bitter (Seville) orange, and lime are central Mexican flavors. Tropical fruits like mango, tamarind, pomegranate, pineapple, coconut (and coconut milk) become more and more prevalent as one travels south.