Thin shards of pastry baked until golden and sharp, piled with soft onion that's sweet from long cooking. The shelf's one ingredient becomes the whole dinner when you have onions and butter at hand.

Serves 2. 50 minutes, 15 at the stove.

About 190 calories a serving, 1 g protein, 10 g carbohydrate, 16 g fat. From USDA figures for 75% of the ingredients; amounts are the recipe's.

Cook mode

1. Heat the oven to 400°F (200°C). Cut one sheet of puff pastry into six rectangles and lay them on a baking sheet. Prick each piece all over with a fork and bake until golden and puffed, about 15 minutes; when the tops turn deep gold, they are done.15 min
2. While the pastry cooks, slice one large onion thin and melt 2 tablespoons butter in a wide skillet over medium heat. Add the onion with a pinch of salt and cook, stirring often, until soft and deeply brown, about 20 minutes; the onion is ready when it tastes sweet and sits in its own caramel.20 min
3. When the pastry comes out, press down the centers gently with the back of a spoon so they don't puff too high. Let cool for a minute, then stir 1 teaspoon dried thyme into the caramelized onion and taste for salt and pepper.
4. Pile the warm onion onto each pastry crisp and serve at once while the pastry is still warm.

Note Swap thyme for rosemary or skip herbs if you prefer. Leftovers keep in the fridge for two days; reheat the pastry in a low oven to restore its crispness, then top fresh. Serve with a sharp green salad on the side to cut through the richness.