- 3 cups fresh corn (about 3 ears)
- 4 scallions, white and green parts thinly sliced separately
- 2 tablespoons unsalted butter
- 2 garlic cloves, minced
- 1 1/2 teaspoons kosher salt
- 1 1/2 teaspoons ground cumin
- 1 teaspoon chili powder
- 1/2 teaspoon black pepper
- 2 plum tomatoes, finely diced
- 1 to 2 fresh jalapeño chiles, finely diced (including seeds)
- 1 (2-pound) trimmed boneless sirloin steak, about 1 1/2 inches thick
- 1/4 cup finely chopped fresh cilantro
- Accompaniment: lime wedges
- Prepare grill for cooking.
- Heat a dry large cast-iron skillet over moderately high heat until hot, then pan-roast corn, stirring occasionally, until golden brown, 8 to 10 minutes. Transfer to a bowl.
- Cook white part of scallions in butter with garlic, 1 teaspoon salt, 1/2 teaspoon each cumin and chili powder, and 1/4 teaspoon pepper in skillet over moderate heat, stirring, until scallions are tender, 3 to 4 minutes. Remove from heat and stir in corn, tomatoes, and jalapeños.
- Combine remaining 1/2 teaspoon salt, 1 teaspoon cumin, 1/2 teaspoon chili powder, and 1/4 teaspoon pepper and sprinkle on both sides of steak. Grill, turning once, until an instant-read thermometer inserted horizontally into thickest part of meat registers 130°F, 18 to 20 minutes total for medium-rare. Transfer steak to a grooved cutting board and let stand 5 to 10 minutes before slicing.
- While steak is standing, reheat corn mixture over moderate heat, stirring occasionally. Stir in cilantro and scallion greens.
- Spoon corn on top of sliced steak and pour over any accumulated juices.