In a small saucepan, saute onion in 1 teaspoon oil until tender; add the wine. Bring to a boil; cook until liquid is reduced to 2 tablespoons. Stir in butter and thyme. Remove from the heat; keep warm.
Place tomatoes on a double thickness of heavy-duty foil. Drizzle with 1 teaspoon oil. Fold foil around tomatoes and seal tightly; set aside. Repeat with whole garlic cloves and remaining oil. Grill garlic, covered, over medium heat for 30 minutes.
Meanwhile, combine the minced garlic, salt and pepper; rub over chops. Grill lamb and tomato packet, covered, over medium heat for 6-8 minutes on each side or until lamb reaches desired doneness (for medium-rare, a meat thermometer should read 145°; medium, 160°; well-done, 170°).
Open tomato packet carefully to allow steam to escape; place tomatoes in a small bowl. When garlic is cool enough to handle, squeeze softened garlic over tomatoes; toss to coat. Serve lamb with tomatoes and wine sauce. Yield: 4 servings.