Ingredients
Method
Instructions
- Heat olive oil and butter in a pan over medium heat. Add the sliced onions and cook until soft and translucent. Sprinkle with sugar and continue cooking until the onions are golden brown and caramelized. Stir in the thyme leaves and season with salt and pepper. Set aside to cool.
- Roll out the thawed puff pastry on a lightly floured surface. Transfer it to a baking sheet lined with parchment paper. Spread a thin layer of Dijon mustard over the pastry, leaving a small border around the edges.
- Sprinkle the grated Gruyère cheese evenly over the mustard layer. Arrange the caramelized onions on top of the cheese, followed by the sliced beefsteak tomatoes. Season the tomatoes with salt and pepper.
- Preheat the oven to 375°F (190°C). Bake the tart for 25-30 minutes, or until the pastry is golden brown and the cheese is bubbly and melted.
- Allow the tart to cool slightly before slicing. Garnish with additional fresh thyme leaves if desired. Serve warm and enjoy!
Notes
Choose ripe tomatoes for the best flavor. Slice tomatoes evenly for uniform cooking. Pat tomato slices dry to prevent a soggy crust. Experiment with different cheeses like Parmesan or sharp cheddar for varied flavors.
