Place marinade ingredients into a bowl and stir to combine.
Add steak pieces to marinade. Marinate for 1-2 hours.
Season onions and peppers to taste with salt and pepper.
Heat the grill. Thread beef, onions and peppers onto skewers. I like to use steel skewers. Be sure to pre-soak wood skewers for a half hour, if using them.
Place the ka-bobs on the grill and cook 4-5 mintes per side. Sprinkle with rosemary and serve.