Combine tomato sauce, lime juice, garlic, cumin, salt, black pepper and cayenne in large plastic food storage bag. Add steak; seal bag. Massage bag to coat steak. Refrigerate 8 hours or overnight.
Heat grill. Grill steak, about 6 minutes per side for medium, until desired doneness, turning halfway through. Let rest then thinly slice.
To assemble salad, toss spinach, carrot and cheese in large bowl. Top with slices of grilled steak. Drizzle dressing over salad. Garnish with fresh cilantro leaves and squeeze of fresh lime, if desired.
