For steak: Place steaks on a large rimmedbaking sheet; season with salt. Mix sugarand next 3 ingredients in a small bowl; ruball over steaks. Cover; refrigerate 1-3 hours.

Let steaks stand at room temperature for1 hour. Build a medium-hot fire in a charcoalgrill, or heat a gas grill to high. Brush grateswith oil. Grill to desired doneness, about 5-7 minutes per side for medium-rare. Letrest for 10 minutes. DO AHEAD: Can bemade 1 day ahead. Let cool; cover and chill.Bring to room temperature before slicing.

For salad: Mix onion and 1 tablespoon vinegar in alarge bowl. Let macerate 10 minutes, tossingoften. Add tomatoes, celery, and olives.

Whisk remaining 2 tablespoon vinegar, olivebrine, horseradish, and next 3 ingredientsin a medium bowl. Slowly whisk in oil. Addto bowl with tomato mixture; toss to coat.Season with salt and pepper. DO AHEAD:Can be made 4 hours ahead. Cover; chill.

Cut steak crosswise into 1/4-thick slices.Serve salad with steak.