How to Make It
Preheat grill to medium-high (about 450°F), or heat a grill pan over medium-high. Toss together tomatoes, 1 tablespoon of the oil, 1/2 teaspoon of the salt, and 1/4 teaspoon of the black pepper in a medium bowl; set aside. Rub steak with 1 tablespoon of the oil and remaining 1 1/2 teaspoons salt and 1 teaspoon black pepper.
Grill tomatoes, turning often, until charred and softened, 4 to 6 minutes. Remove from grill, and let cool until ready to use. Grill steak, turning occasionally, until lightly charred and medium-rare, 8 to 10 minutes. Transfer to a board, and let rest, 5 to 10 minutes.
Coarsely chop tomatoes, and transfer to a medium bowl. Add parsley, vinegar, garlic, sugar, crushed red pepper, and remaining 1 tablespoon olive oil, and toss to combine.
Slice steak against the grain, and spoon tomato relish over top.