Prepare Steak & Vegetables: Trim fat from steak. Cut steak into four equal portions. Sprinkle chili powder and 1/8 teaspoon of the salt over the steak portions. Thread tomatoes onto four 6- to 8-inch skewers (see Tip). Lightly coat tomatoes and both sides of the zucchini and red onion slices with nonstick spray. Sprinkle vegetables with the remaining 1/8 teaspoon salt.

For a charcoal grill, place steak, tomato skewers and vegetable slices on the rack of an uncovered grill directly over medium coals. Grill steak until desired doneness, turning once halfway through cooking. Allow 14 to 18 minutes for medium-rare doneness (145 degrees F) or 18 to 22 minutes for medium doneness (160 degrees F). Grill zucchini and onion slices for 10 to 12 minutes or until tender and lightly charred in places, turning occasionally. Grill tomatoes for 4 to 6 minutes or just until softened and lightly charred, turning once. (For a gas grill, preheat grill. Reduce heat to medium. Place steak, tomato skewers, and vegetable slices on grill rack over heat. Cover and grill as above).

Prepare Chimichurri Sauce: Combine parsley, cilantro, vinegar, water, olive oil, garlic, salt, ground black pepper and, if desired, crushed red pepper in a blender or food processor. Cover and blend or process with several on/off pulses until chopped, but not pureed.

Slice steak and divide among four serving plates. Serve with grilled tomatoes, vegetable slices and Chimichurri Sauce.