Brush the tomatoes and corn with the oil. Clean and oil grate.
Place the tomatoes, cut side down, on the grill, along with the corn. Cook, carefully turning the tomatoes once, and the corn frequently, until they are charred in spots. Transfer to a cutting board and let sit until cool enough to handle. Chop the tomatoes finely and cut kernels from the corn cobs. Place in a bowl with red onion, cilantro, jalapeño, lime juice and remaining 1/4 teaspoon salt. Set aside.
Pat the steaks dry with paper towels, season with pepper and place on cooler side of grill. Cover and cook, with vents open, turning and using an instant-read thermometer to take the temperature every few minutes, until steaks register 105 degrees for medium-rare or 115 degrees for medium, 8 to 10 minutes total.
Move the steaks to the hot side of grill and cook, turning frequently, until a dark crust has developed and thermometer registers 125 degrees for medium-rare or 135 degrees for medium, about 2 to 3 minutes total.
Let steaks rest 5 to 10 minutes and cut into slices. Serve steak with salsa and lime wedges on the side.