Heat a nonstick skillet coated with cooking spray over medium-high heat until hot. Add beef, and sauté 2 minutes; remove beef from pan. Add onion and garlic to pan, and sauté 2 minutes. Stir in beans and broth; cook 1 minute. Mash bean mixture with a fork; stir in pepper and cumin. Spread bean mixture over tortilla, and top with 2 tablespoons sour cream, spreading to cover. Place beef strips down center of tortilla; top with 1 tablespoon salsa. Roll up tortilla; place, seam side down, on a microwave-safe plate. Microwave at HIGH 1 minute or until burrito filling is hot. Top with 1 tablespoon sour cream, 1 tablespoon salsa, and lettuce.