LEAN BEEF ON THE GRILL America’s favorite summer grilling meat is leaner than ever before. The leanest beef cuts benefit from marinating when grilled to make them tender and juicy. Marinades are seasoned liquid mixtures that not only add flavor, but in some cases help tenderize a beef cut. A tenderizing marinade must contain an acidic ingredient such as lemon juice, yogurt, wine or vinegar, or a natural tenderizing enzyme found in fresh papaya, ginger, pineapple and figs. Which beef cuts do you marinate? Tender beef cuts should be marinated for only 15 minutes or up to 2 hours to add flavor. These include: Porterhouse/T-bone, top loin, tenderloin, rib eye, rib, top sirloin, chuck eye and chuck top blade steaks. Less tender cuts should be marinated for at least 6 hours or as long as overnight in a mixture containing a food acid or tenderizing enzyme. These include flank, skirt, top round, round tip and chuck steaks. These tips ensure great marinating results:      •Always marinate in the refrigerator, never at room temperature.      •Marinating longer than 24 hours in a tenderizing marinade can result in a mushy texture. (A tenderizing marinade only penetrates about ¼ inch into the cut surface of beef.)      •If a marinade is to be used later for basting or served as a sauce, reserve a portion of it before adding the beef. If marinade has been in contact with uncooked meat, bring it to a full rolling boil before using as a sauce.      •Never save and reuse a marinade.      •Allow ¼ to ½ cup marinade for each 1 to 2 pounds of beef.      •Marinate in a food-safe plastic bag or a glass utility dish. Select dishes in which the beef will fit snugly, but lie flat. Turn or stir the beef occasionally to allow even exposure to the marinade.