Trim the steak and cut into 1-inch cubes. In a small bowl, whisk the marinade mix with the oil, water and vinegar. Reserve ¼ cup of the marinade for basting later. Place the meat in a large bowl or resealable gallon freezer bag and add the marinade, tossing to coat well.

Refrigerate for 30 minutes up to overnight. Remove the meat from the marinade and discard the leftover marinade.

Cut the bell peppers into 1-inch pieces. Thread the steak with the peppers, alternating the steak with the peppers in a rainbow of colors.

Grill over medium high heat, turning once or twice and basting with the reserved marinade with each turn.