In a bowl, whisk together the balsamic vinegar, olive oil, Dijon mustard, dried oregano, dried rosemary, minced garlic, salt, black pepper, honey, and lemon zest until well combined. This creates a balanced marinade with acidity, richness, and aromatic depth. While the marinade sits, prepare your vegetables: cut the bell peppers into 1-inch squares, cut the steak into 1-inch cubes, and keep the cremini mushrooms and cherry tomatoes whole. Pat the beef dry with paper towels—this helps it absorb the marinade better and will encourage better browning on the grill.

Thread the beef cubes, mushrooms, cherry tomatoes, bell pepper squares, and red onion chunks onto 8 metal or wooden skewers (if using wooden skewers, soak them in water for 30 minutes first to prevent burning). Alternate the ingredients as you thread to ensure even cooking and attractive presentation. Place all assembled skewers in a large dish or resealable container, then pour the marinade from Step 1 over them, making sure each skewer is well coated. Cover and refrigerate for at least 2 hours, or up to 8 hours—I find that even 3-4 hours gives excellent flavor without the beef becoming too tender and losing its texture.

Remove the skewers from the marinade and let excess sauce drip back into the dish—discard the remaining marinade since it's been in contact with raw beef. Preheat your grill to medium-high heat (around 400°F if using a gas grill). Place the skewers directly on the grill grates and cook for 6-8 minutes, turning every 2 minutes to ensure even charring and cooking on all sides. The beef should reach medium doneness (an internal temperature of 130-135°F), while the vegetables will caramelize beautifully. I prefer turning the skewers more frequently rather than less—this prevents any side from burning while keeping the meat juicy and the vegetables tender-crisp.

Transfer the grilled kabobs to a serving platter and let them rest for 2-3 minutes before serving. This brief rest allows the juices to redistribute throughout the beef, ensuring each bite stays tender and flavorful. Serve immediately while still warm.