Ingredients
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1 large yellow onion
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3 tbsp olive oil
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1/2 tsp dried thyme
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1 (8 oz) pkg sliced white mushrooms
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1 tbsp sherry vinegar
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1/2 (17.3 oz) box frozen puff pastry sheets, thawed
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1 tbsp finely chopped parsley
Steps
1
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.
2
While onion cooks, chop the mushrooms. Line a large baking sheet with parchment.
3
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.
4
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.
5
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.
Tips
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.
