Sweet onions are hit with a dash of sherry vinegar for a sweet-and-sour topping that perfectly complements the flaky golden pastry underneath.
- 1 large yellow onion
- 3 tbsp olive oil
- ½ tsp dried thyme
- 1 (8 oz) pkg sliced white mushrooms
- 1 tbsp sherry vinegar
- ½ (17.3 oz) box frozen puff pastry sheets, thawed
- 1 tbsp finely chopped parsley
- Preheat oven to 400°F. Finely chop the onion. In a 12-inch skillet, heat the oil on medium. Add onion and thyme. Cover and cook 20 min., until golden, stirring occasionally. Turn oven to 425°, uncover, and cook another 5 min.
- While onion cooks, chop the mushrooms. Line a large baking sheet with parchment.
- Add mushrooms to skillet. Cook 10 min., stirring occasionally. Stir in the vinegar. Season with salt and pepper to taste. Remove from heat and cool 10 min.
- Unfold the puff pastry sheet on the lined baking sheet. Roll pastry out as thinly as possible. Spread mushroom mixture over pastry in an even layer.
- Bake 25–30 min., until pastry is golden brown, rotating the pan halfway through cooking time. With a pizza cutter, slice into 5 columns and 5 rows to form 25 bite-size pieces. Garnish with chopped parsley.
The onion and mushroom mixture can be prepared up to 48 hours in advance and refrigerated. To reheat, microwave 1 min. until no longer cold before spreading on pastry.
- December 2018