Preheat your oven's broiler to high or fire up your outdoor grill to medium-high heat.

Pat the sirloin dry with paper towels and cut into 1-inch cubes.

In a mixing bowl, combine beef cubes with olive oil, salt, rosemary, garlic, and black pepper. Mix well and let sit for 15-20 minutes.

Thread the marinated beef onto skewers, adding optional veggies if desired. Arrange on a baking tray.

Broil or grill the kabobs for 4-5 minutes without disturbing them for a nice char.

Flip the skewers and cook for another 4-5 minutes until desired doneness is reached.

Remove from heat and allow skewers to rest for 5 minutes before serving.