Grilled Flank Steak with Tomato-Feta Salad

Pat steak dry with paper towels and sprinkle with 1½ teaspoons sugar, Greek seasoning, ½ teaspoon salt, and pepper. Whisk oil, shallot, mint, 1 tablespoon vinegar, remaining ½ teaspoon sugar, and ¼ teaspoon salt together in bowl. Arrange tomatoes in even layer on large platter.

Grill steak over hot fire (covered if using gas) until browned on both sides and steak registers 125 degrees (for medium-rare), 6 to 10 minutes, flipping every 2 minutes. Transfer steak to wire rack set in rimmed baking sheet and let rest for 10 minutes.

Cut steak in half lengthwise, with grain, then slice each half thin against grain. Transfer to platter. Mix 2 tablespoons dressing with remaining 1 tablespoon vinegar and drizzle over steak. Stir feta into remaining dressing. Sprinkle tomatoes evenly with remaining ¼ teaspoon salt, then spoon feta mixture over top. Serve.