PREPARATION:

1. Place half the beans in bowl of food processor fitted with metal blade. Add remaining ingredients except buns, salsa, avocado and reserved beans. Pulse 30 to 40 seconds until mixture begins to hold together. Add remaining beans; pulse 3 to 4 times until just mixed. Let sit 20 minutes at room temperature for flavors to develop.
2. Preheat oven to 350°F.
3. Shape mixture into 6 patties (about 1/4 cup each). Spray 12-inch skillet with cooking spray and place over medium heat. Add 4 patties; cook, covered, 4 to 5 minutes or until browned. Spray tops of patties with cooking spray; turn and cook other side 4 to 5 minutes or until browned. Repeat with remaining patties.
4. For firmer patties, place browned patties on baking sheet; bake 12 to 15 minutes. Or, for moister patties, serve after pan-frying. Serve between buns topped with salsa and avocado slices, if desired.