
Combine the steak with (half of) the sauce in a large ziplock bag or bowl, and toss until the steak is evenly coated. Seal or cover, then refrigerate for at least 30 minutes, or up to 8 hours.
Once you’re ready to cook the skewers, heat grill to medium-high heat.
Thread the skewers alternately with the marinated steak, peppers and onions. Brush each skewer liberally with the remaining marinade, and season each with a pinch of salt and pepper. Grill the skewers for 2-3 minutes per side, turning once, or until the steak is cooked to your desired level of doneness. Remove skewers from grill and let rest for 5 minutes. Brush each kabob evenly with the remaining sauce (the half that was not used for the marinade).
Serve immediately.
Whisk all ingredients together until combined. Set aside half of the sauce to be used as a dipping sauce, and half to be used as a marinade.