In a 9 x 13 casserole dish, add your olive oil, balsamic vinegar, garlic and rosemary. Now, add your steak and give it all a mix so the steak is evenly coated. Cover with saran wrap and place in the refrigerator for at least one hour and up to eight hours.
Take the steak out of the refrigerator one hour before you want to cook. It’s best if the steak comes to room temperature so it will cook evenly. Place them on your skewers.
Heat your grill to medium high. Oil the grill. I like to season my grill with avocado oil. You could also use a cooking spray (just be careful of flareups).
Place the skewers on the grill and cook for 3-4 minutes per side. When done, take the skewers off the grill and let them rest for 5 minutes before serving. Enjoy!