Tender steak kabobs with colorful peppers and onions are a high protein, carnivore-approved grilled favorite. This family-style dish makes dinner fun and flavorful right off the grill.
Cut the sirloin steak into 1.5-inch cubes for even grilling and set aside in a large bowl.
Prepare the vegetables: slice the red, yellow, and green bell peppers and the red onion into 1.5-inch pieces, and trim mushrooms if needed.
In a small bowl, whisk together olive oil, soy sauce, Worcestershire sauce, garlic powder, black pepper, and kosher salt to create the marinade.
Combine the steak cubes with half the marinade in a resealable bag or bowl; toss to coat and marinate in the refrigerator for at least 30 minutes, up to 2 hours for best flavor.
When ready to cook, thread steak cubes, peppers, onions, and mushrooms alternately onto skewers, leaving small gaps between pieces for even heat.
Preheat the grill to medium-high heat (about 400°F/205°C). Oil the grates with a brush to prevent sticking.
Grill kabobs for 8–10 minutes total, turning every 2–3 minutes for even browning. Brush remaining marinade over kabobs during grilling.
Remove from grill when steak reaches desired doneness (medium-rare at 135°F) and vegetables are lightly charred but still crisp-tender. Let rest for 3 minutes before serving.