Updated Apr 7, 2017Chatelaine
red onion, thinly sliced into rounds
1/2 397-g pkg
frozen puff pastry, thawed
asparagus, about 250 g, trimmed and sliced in half lengthwise
kalamata olives, pitted and sliced
grated fontina or mozzarella
- Heat a large non-stick frying pan over medium. Add 1 tbsp oil, then onion. Sprinkle with sugar and 1/8 tsp salt. Cook, stirring occasionally, until caramel coloured, about 12 min. Stir in vinegar.
- Position oven rack in lower third of oven. Preheat to 400F. Line a baking sheet with parchment paper. Roll out pastry on a lightly floured surface into a 14×10-in. rectangle. Pastry will be thin, and edges will be uneven. Transfer to lined baking sheet. Beat egg with 1 tbsp water in a small bowl. Lightly brush pastry with egg wash. Set aside.
- Drizzle asparagus with remaining oil and sprinkle with remaining salt. Season with fresh pepper. Toss to coat.
- Scatter caramelized onion and olives over pastry. Sprinkle with 1/2 of cheese. Arrange asparagus spears in 2 parallel rows on cheese. Sprinkle with remaining cheese. Bake in lower third of oven until pastry has puff ed up and cheese is melted, 20 to 25 min. Cut into bite-sized rectangles and serve immediately.