Combine onions and flour in a large resealable plastic bag; lightly crush with hands or rolling pin. Dip chicken in eggs. Add a few pieces at a time to the onion mixture; shake to coat. Place on a greased 15-in. x 10-in. x 1-in. baking pan.
Bake, uncovered, at 400° for 15 minutes or until chicken juices run clear. Meanwhile, combine the sour cream, pepper sauce and dip mix. Serve chicken with dip and mustard.