1Saute onion in hot oil in a large skillet over medium-high heat 4-5 minutes or until onions are caramel colored.
2Add ground beef to skillet, and cook over medium-high heat, stirring often, 5-6 minutes or until meat crumbles and is no longer pink; drain.
3Return beef mixture to skillet. Stir in tomato paste and next 2 ingredients, and cook, stirring occasionally, 3-4 minutes or until mixture thickens and color darkens. Stir in cola and 1/2 cup water and cook, stirring constantly for 6-8 minutes or until bubbly. Remove from heat and stir in pepperoncini peppers; add salt and red pepper to taste.
4Serve beef mixture imediately on buns with coleslaw.