Prep 10 Total 55 min

4 large tomatoes (about 2 pounds), cut crosswise into 1/2-inch slices
1 large or 2 medium red onions (about 1 pound), cut crosswise into 1/4-inch rounds
2 tablespoons extra-virgin olive oil
Coarse salt and ground pepper

4 large tomatoes (about 2 pounds), cut crosswise into 1/2-inch slices 1 large or 2 medium red onions (about 1 pound), cut crosswise into 1/4-inch rounds 2 tablespoons extra-virgin olive oil

Preheat oven to 450 degrees. In a 9-by-13-inch baking dish, arrange tomatoes and onions in rows, overlapping slightly. Drizzle with oil and season with salt and pepper. Bake until tomatoes are lightly browned and onions are tender, about 45 minutes. Serve warm or at room temperature.