Pineapple-Gruyere Burgers
["4 1/2-inch thick rings of peeled and cored pineapple", "vegetable oil", "1 1/2 lb. freshly ground chuck", "salt and pepper", "4 (1/2-inch thick) slices Gruyere cheese", "4 burger buns", "2 c. mixed baby lettuce", "8 thin slices red onion", "12 thin slices tomato"]
["Light a grill or preheat the broiler.", "Grill pineapple on an oiled rack or broil until golden brown (3 minutes per side). Shape the ground chuck into four (3 1/2-inch) patties and season on both sides with salt and pepper.", "Grill the burgers on an oiled grill rack or broil for 4 minutes.", "Turn and cook for 3 minutes.", "Place a slice of Gruyere cheese on each burger and cook until the cheese is melted, 1 minute.", "Grill or toast buns.", "Place burgers on buns and top each with a pineapple ring.", "Mound baby lettuce. Serve with red onion and tomato slices."]
["rings", "vegetable oil", "freshly ground chuck", "salt", "Gruyere cheese", "buns", "baby lettuce", "red onion", "thin slices tomato"]