- 1 large red onion, halved and sliced 1/4 inch thick
- 2 red bell peppers, ribs and seeds removed, sliced 1/4 inch thick
- 1 can (20 ounces) cannellini beans, drained and rinsed
- 2 tablespoons plus 1 teaspoon olive oil
- 1 tablespoon fresh rosemary leaves (or 1 teaspoon dried rosemary, crumbled)
- Coarse salt and ground pepper
- 1 1/2 pounds flank steak (1 piece)
- 1 tablespoon red-wine vinegar
- Heat broiler. If using a broilerproof rimmed baking sheet, set rack 4 inches from heat; if using a broiler pan, set rack so that top of pan is 4 inches from heat. On sheet (or pan), toss onion, peppers, and beans with 2 tablespoons oil, rosemary, 1 teaspoon salt, and 1/4 teaspoon pepper.
- Push bean mixture to one side of sheet (or pan); place steak on other side. Rub steak with remaining teaspoon oil; season generously with salt and pepper. Broil, tossing bean mixture occasionally, until steak is medium-rare (135 degrees on an instant-read thermometer) and vegetables are lightly charred, 12 to 16 minutes.
- Transfer steak to a cutting board; cover loosely with foil, and let rest in a warm place for at least 5 minutes. Transfer bean mixture to a serving bowl; toss with vinegar. Slice steak thinly; serve with bean mixture.