1. In large bowl, mash beans with a fork. Add the rice, onion, egg and 2 tablespoons salsa, mix well. Drop by 1/2 cupfuls into a large nonstick skillet coated with nonstick cooking spray. Flatten to 1/2 in thickness. Cook over medium heat for 4 -5 minutes on each side or until firm and browned.
2. In a small bowl, combine sour cream and remaining salsa. Place a lettuce leaf, burger, sour cream mixture and sliceof cheese on bun.