1. Divide beef into quarters. Shape each piece into a 3/4-inch-thick patty.
2. Prepare a covered grill for direct grilling. Combine salt and pepper in a cup; sprinkle over both sides of patties. Grill patties about 15 minutes, turning every 4 minutes until an instant-read meat thermometer inserted in the side of each burger registers 160 degrees F.
3. While burgers are cooking, grill muffins, cut side down, for 1-1/2 to 2 minutes, until toasted. Rub garlic on toasted side, then brush each half with oil.
4. Place basil leaves on bottom halves of muffins. Top with burgers, tomato slices and top halves of muffins. Makes 4 servings.