If using wooden skewers, soak them in water for at least 30 minutes prior to grilling.
In a small bowl, whisk together the balsamic vinegar, olive oil, minced rosemary, minced garlic, salt, and black pepper to create the marinade.
Place the cubed beef in a shallow dish, pour half of the marinade over the meat, and toss to coat. Let marinate for at least 30 minutes in the refrigerator.
Parboil the baby potatoes in salted water for about 5 to 7 minutes until just fork-tender, then drain and let cool.
Thread the marinated beef, zucchini, yellow bell pepper, red bell pepper, red onion, cherry tomatoes, and parboiled potatoes onto the skewers, leaving a small gap between pieces for even cooking.
Preheat the grill to medium-high heat and lightly oil the grates.
Grill the skewers for 10 to 15 minutes, turning occasionally, and brushing with the remaining unused balsamic marinade during the last 5 minutes of cooking.
Remove from the grill and let rest for 3 to 5 minutes before serving.