- 3 tablespoons olive oil, divided, plus more for the grill
- 1 red onion, cut into 4 (½-inch-thick) slices
- 2 teaspoons kosher salt, divided
- 1 teaspoon black pepper, divided
- 1¼ to 1½ pounds skirt steak, cut crosswise into 4 (6-inch) pieces
- 8 slices thickly cut bread (such as sourdough)
- 2 ounces (¼ cup) unsalted butter, melted
- 8 (1-ounce) Havarti cheese slices
- Romesco Sauce (see below)
- Preheat grill to medium-high. Brush the grill grates with oil. Brush the onion with 1 tablespoon of the oil and sprinkle with ½ teaspoon of the salt and ¼ teaspoon of the pepper. Brush the steak with the remaining oil and season with the remaining salt and pepper.
- Grill the onion, covered, until tender and charred, 6 to 8 minutes per side. Grill the steak, 3 to 5 minutes per side for medium-rare. Remove the onion and steak from grill. Let the steak stand for 5 minutes, then slice across the grain.
- Brush one side of each bread slice with the butter. Top 4 of the bread slices with 1 cheese slice each. Grill all of the bread, covered, until the bread is toasted and the cheese is melted, 1 to 2 minutes. Divide the steak among the 4 pieces of plain toast; add 1 slice of onion and 1 tablespoon Romesco Sauce to each. Top with the remaining toast, cheese-side down, and serve.
Process 1 (12-oz.) jar roasted red peppers, drained; 1 chopped garlic clove; 2 Tbsp. roasted almonds; 1 tsp. kosher salt; ¼ tsp. black pepper; and 4 tsp. red wine vinegar in a food processor until almost smooth. Other uses: Fold into an omelet, top a grilled steak, or swirl into spaghetti.