Sweet Onion-Tomato Tartlets

3 cups grape tomatoes
1 sweet onion, quartered and thinly sliced (about 2 cups)
2 tablespoons olive oil
1 tablespoon snipped fresh rosemary
½ teaspoon salt
½ teaspoon ground black pepper
1 tablespoon red wine vinegar
1 package (2 sheets) frozen puff pastry sheets, thawed
Manchego cheese shavings

Preheat oven to 400 degrees. Prick tomatoes with a fork or the tip of a sharp knife. In an ungreased 15x10x1-inch pan, combine tomatoes, onion, oil, rosemary, salt and pepper. Roast for 25 to 30 minutes or until onion is tender. Remove from oven. Sprinkle with vinegar, cool.
Meanwhile, line a large baking sheet with parchment paper. On a lightly floured surface, unfold puff pastry. Using a 3-inch round cookie cutter, cut pastry into rounds. Place rounds on the prepared baking sheet. You can purchase precut pastry rounds as well.
Spoon about 2 tablespoons of the roasted tomato mixture onto each pastry round. Place onion first, then tomatoes and then top with more onion. Bake for 15 to 20 minutes or until edges are puffed and golden brown. Let stand on baking sheet for 5 minutes before serving. Garnish with cheese.

Makes about 18 tartlets.
National Onion Association