1. Spray grate of outdoor grill with grilling spray. Preheat grill to medium heat according to manufacturer's directions. Meanwhile, set aside 1/3 cup drained tomatoes. Mix together beef, remaining drained tomatoes, salt and pepper in medium bowl. Shape into 4 patties, about 1/2-inch thick.
2. Grill patties 10 minutes or until cooked through (160 degrees F), turning once. Top each patty with 1 slice cheese; melt slightly.
3. Place patties on bottom halves of buns. Top each patty with 3 or 4 avocado slices and a generous tablespoon of reserved tomatoes. Close with tops of buns. Serve immediately.