In a resealable plastic bag or shallow dish, combine vinegar, sugar, garlic, rosemary, 1 teaspoon coarse salt, and 1/2 teaspoon pepper. Pierce meat all over with a fork; add to marinade, and turn to coat. Let marinate at room temperature at least 15 minutes, or cover and refrigerate up to 1 day.
Heat grill to high; oil grates. Remove steaks from marinade, allowing excess to drip off. Grill steaks 2 to 4 minutes per side for medium-rare. Transfer to a plate; cover loosely with aluminum foil, and let rest 5 minutes.
Perfect quick and east grill recipe. Having used soy sauce marinades before I now officially prefer using balsamic vinegar. The balsamic is sweeter, especially once mixed with brown sugar and the fat on the meat, and no where near as salty as soy sauce. I served it on a bed of arugula with a side of caramelized barbecued corn.