Pour the vinegar, lemon juice, rosemary, salt, and pepper over the steak chunks in a bowl or bag. Let it marinade either covered in the refrigerator for 2 hours or on the countertop for 15 minutes.
Using either a metal or wooden skewer, spear the meat, fresh fig, and onion chunks. Repeat this order until the skewer is full.
On a hot grill, grill each side for about 3 minutes.
Remove from the grill and let rest for 5 minutes so the juices can settle.
Remove skewer, plate, and enjoy!