Cut steak into 1-inch cubes. Add to a shallow bowl and set aside.
Prepare the marinade by whisking marinade ingredients together in a bowl. Pour over the steak and allow it to marinate for at least 30 minutes (and up to 8 hours) in the fridge.
Preheat the grill to medium-high heat (400-450℉).
Assemble kebabs by threading the steak, onions, and bell peppers onto skewers* alternating as you go.
Place kebabs directly on the grate of the preheated grill and cook 4-5 minutes per side until the desired degree of doneness.
