1Mix 1/2 cup Coca Cola, pineapple juice, soy sauce, vinegar, Worcestershire sauce, tomato paste, 2 Tbsp brown sugar, garlic powder, red pepper flakes and onion in covered container: marinate steak overnight in refrigerator.
Remove steak cubes and onion pieces from refrigerator. Reserve marinade.
2Add marinade to small saucepan. Bring to a boil over hight heat. Spoon 2 Tbsp marinade into small bowl and stir conrstarch into hot liquid until mixture is smooth. Return liquid to pan. Stir in remaining 2 Tbsp brown sugar and chili-garlic sauce. Reduce heat to medium and simmer 15 to 18 minutes until thickened and reduced to 1 cup. Season to taste with salt and black pepper.
3Meanwhile, place steak cubes on 6 skewers, alternating evenly with the onion pieces. Broil 3 minutes, turn and broil 2 minutes.
Glaze kabobs with sauce using a clean pastry brush. Serve over rice, if desired.
*Chili-garlic sauce can be found in the Asian foods section of the grocery store.