Choose Wisely

• Some marinades are designed to just flavor meat rather than tenderize it. To make sure your marinade will get the job done on tough lamb, use a tenderizing acidic ingredient that is also high in moisture-adding fat. Or blend acidic ingredients with fatty ingredients -- vinegar and oil are a classic example of this pairing. Resealable plastic bags are ideal for combining the lamb pieces with the marinade. A 1- to 2-cup portion of marinade is usually enough to tenderize a few pounds of lamb.

Go to Yogurt

• Yogurt contains the enzymes that help break down fibers in meats. At the same time, its creamy quality provides moisture. Use whole milk yogurt for the highest fat content. Greek-style yogurt is ideal, because it is creamier than more watery, traditional yogurts. Add the juice of a lemon for further tenderizing, and flavorings such as mint, cardamon and coriander. When the kebabs go on the grill, leave a light coating of the marinade on the lamb pieces.

Bust out the Buttermilk

• Like yogurt, buttermilk provides both tenderizing acidity and some fat content for locking in the meat's juices. Flavor buttermilk with garlic, mint, parsley and other aromatics, and toss most of it with the lamb meat. If possible, keep some of the marinade for additional basting while the kebabs are on the grill.

Juice it Up

• Citrus juices have the acidity necessary to break down tough meats. A combination of 3 parts orange juice to 1 part lime juice imparts a blend of flavors and contributes tenderizing qualities. Pair these juices with 2 parts extra virgin olive oil, a fat especially good at penetrating deeper into the meat once the acids break down the proteins. Flavoring possibilities include fresh Mediterranean herbs, garlic, cumin and pepper.

Toss with Tartness

• Various types of vinegar can help break down lamb meat's toughness because of their high acid content. Choose one that pairs well with the other seasonings in the kebab dish -- fruity apple cider vinegar for pomegranate sauce, for example, or red wine vinegar for kebabs with earthy vegetable chunks. Blend 1 part vinegar to 2 parts olive oil for maximum moisture and a taste that's not overly tart.

Wine and Dine

• Wine is both rich in flavor and acidic, so it makes a useful marinade for lamb kebab pieces. Use equal parts red wine and olive oil to intensify the acidifying action.