1. For marinade, in a large, shallow glass dish, combine tomatoes, garlic, vinegar and pepper flakes. Rinse steaks and pat dry; add to marinade, turning to coat all sides. Cover and marinate at room temperature 30 minutes (or refrigerate up to 5 hours).
2. Heat broiler and place rack 4 inches from heat. Cover a rimmed baking sheet or broiler pan with foil. Transfer steak and marinade to baking sheet and sprinkle with 1 tsp. salt. Broil, turning once, until an instant-read thermometer inserted in center registers 145 degrees F for medium, 10 to 14 minutes. Remove from broiler and let stand 5 minutes before cutting into 1/2-inch-thick slices; reserve cooked marinade.
3. Meanwhile, cook pasta according to package directions. Drain and transfer to a large bowl. Toss with pesto and remaining 1 tsp. salt.
4. Transfer steak to a platter; top with half the cooked sauce. Serve with pasta and remaining sauce. Makes 8 to 10 servings.