In a medium-sized mixing bowl, whisk together olive oil, soy sauce, balsamic vinegar, Worcestershire sauce, minced garlic, Dijon mustard, black pepper, and rosemary until well combined.

Place the steak cubes in a resealable plastic bag, pour the marinade over it, seal, and massage the marinade into the meat. Marinate in the refrigerator for at least 30 minutes, preferably 2 hours.

Wash and chop the bell peppers, slice the red onion, and cut the zucchini into rounds. Rinse the mushrooms.

Thread the steak and vegetables onto skewers, alternating between each ingredient.

Preheat the grill to medium-high heat, oil the grates, and prepare to cook the kabobs.

Place the skewers on the grill and cook for about 3 minutes without moving. Flip when they release easily, then continue grilling.

Turn every 2-3 minutes until the steak reaches the desired doneness, approximately 8-10 minutes total cooking time.

Remove from the grill, cover with foil, and let rest for 5 minutes before serving.