6 medium-size plum or campari tomatoes, halved lengthwise
3 tablespoons olive oil, divided
2 teaspoons kosher salt, divided
1 1/4 teaspoons black pepper, divided
1 1/2 pounds flat iron steak
1/4 cup firmly packed fresh flat-leaf parsley leaves, coarsely chopped
1 tablespoon red wine vinegar
1 garlic clove, finely chopped
1 teaspoon granulated sugar
1/4 teaspoon crushed red pepper
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.