Much of the produce in the Mexican kitchen -- for example, tomatoes, potatoes, radishes and plantains -- can be purchased in any American supermarket.

Then there are the exceptions -- fruits and vegetables that add an authentic flavor, color or crunch to a Mexican dish. We found the following selection at El Primo Grocery in the Riverdale area, in Little Mexico:

GUAJE (WAH-heh ) Pictured at top; a member of the bean family, guaje is a long, flat, green, foot-long pod filled with small, flat seeds that have a strong, garlicky flavor. Chop whole pods and add to meat or vegetable stews. Raw or toasted seeds can be eaten as a snack or added to guacamole, salads or soups.

MAMEY (mah-MAY) An oval-shaped, cantaloupe- sized fruit with a thick, rough, brown skin. The soft, orange-red flesh is similar in texture to papaya and surrounds a smooth, brown pit. The flavor is very sweet and brings to mind sweet potato with a touch of almond. Peel and pit the mamey, add a drizzle of lime juice, eat with a spoon. Blend into a shake.

PAPALO (PAH-pa-loh) A pungent herb with beautiful, scalloped, green-blue leaves. It tastes like a combination of watercress, cilantro and rue with a lemony touch of sorrel. Papalo is usually eaten raw in salads, in sandwiches or tacos. Float fresh leaves atop a soup or strew over grilled meats. It can also be minced and added to guacamole.

PEPICHA (peh-PEE-cha) A tender annual herb with the appearance of tarragon and a flavor that is subtle and grassy with a hint of parsley. Mince and add to green salsas. Chopped pepicha is a seasoning for summer squash as well as soup. Stuff a little in a quesadilla.

TUNA (TOO-nuh) The fruit of the nopal cactus, the tuna (pictured at right), is lemon-sized and -shaped. The mottled green skin is studded with tiny pads of fine spines. Tuna is easily peeled after scoring with a knife, and its honeydew-flavored flesh is loaded with hard, black, edible seeds. Dice and add to fruit salads. Slice and eat with a squeeze of lime.