Combine minced garlic, olive oil, chopped rosemary, salt, and black pepper in a mixing bowl, stirring until well blended to create a marinade.
1.5 pounds beef sirloin, 4 cloves garlic, 2 tablespoons olive oil, 2 teaspoons fresh rosemary, to taste salt and black pepper
Add the beef cubes to the marinade and toss to coat evenly. Cover the bowl with plastic wrap and refrigerate for at least 15 minutes to allow flavors to penetrate.
1.5 pounds beef sirloin
Preheat the grill to medium-high heat (about 400°F). Thread the marinated beef cubes onto skewers, about 4-5 pieces per skewer.
1.5 pounds beef sirloin
Place the skewers on the hot grill grates and cook for 4-5 minutes per side, turning with tongs, until the beef develops a deep brown, slightly charred exterior and is cooked to your preferred level of doneness.
Remove the kebabs from the grill once evenly browned and cooked through. Let rest for 2 minutes, then transfer to a serving plate. Garnish with additional rosemary if desired and serve hot.