Grill steaks, covered, over medium heat or broil 4 in. from the heat for 5-7 minutes on each side or until meat reaches desired doneness (for medium-rare, a meat thermometer should read 145°; medium, 160°; well-done, 170°).
Meanwhile, in a large bowl, combine the tomatoes, onion, artichokes and mushrooms. In a small bowl, whisk the vinegar, oil, sugar, salt, oregano, rosemary, pepper and garlic. Pour over vegetable mixture; toss to coat.
Thinly slice steaks across the grain. Add beef and spinach to vegetable mixture; toss to coat. Yield: 6 servings.