Beefsteak Tomato Tart with Caramelized Onions & Thyme
Beefsteak Tomato Tart with Caramelized Onions & Thyme

Indulge in the rich flavors of summer with this Beefsteak Tomato Tart with Caramelized Onions & Thyme. This dish combines the sweetness of caramelized onions, the juiciness of beefsteak tomatoes, and the aromatic touch of thyme, all nestled in a flaky, buttery crust. Perfect for a light lunch or a sophisticated dinner, this tart is sure to impress your guests and satisfy your taste buds.

Ingredients
- 1 sheet puff pastry, thawed
- 2 large beefsteak tomatoes, sliced
- 2 large onions, thinly sliced
- 2 tablespoons olive oil
- 1 tablespoon butter
- 1 teaspoon sugar
- 1 tablespoon fresh thyme leaves
- Salt and pepper to taste
- 1 cup grated Gruyère cheese (optional)
- 1 egg, beaten (for egg wash)
Step-by-Step Instructions
1. Caramelize the Onions
Heat the olive oil and butter in a large skillet over medium heat. Add the thinly sliced onions and cook, stirring occasionally, until they begin to soften. Sprinkle the sugar over the onions and continue cooking, stirring frequently, until the onions are golden brown and caramelized. This process can take about 20-25 minutes. Once done, stir in the fresh thyme leaves and season with salt and pepper. Set aside to cool.
2. Prepare the Puff Pastry
Preheat your oven to 375°F (190°C). Roll out the thawed puff pastry on a lightly floured surface to fit your tart pan. Transfer the pastry to the tart pan, pressing it gently into the edges. Trim any excess pastry from the edges. Using a fork, prick the bottom of the pastry to prevent it from puffing up during baking.
3. Assemble the Tart
Spread the caramelized onions evenly over the bottom of the puff pastry. Arrange the beefsteak tomato slices on top of the onions, slightly overlapping them. Sprinkle the grated Gruyère cheese over the tomatoes, if using. Brush the edges of the pastry with the beaten egg to create a golden, glossy finish.
4. Bake the Tart
Place the tart in the preheated oven and bake for 25-30 minutes, or until the pastry is golden brown and the tomatoes are tender. Remove from the oven and let it cool slightly before serving.
Expert Tips
- Choose Ripe Tomatoes: For the best flavor, select beefsteak tomatoes that are ripe but still firm. This ensures they hold their shape during baking.
- Low and Slow Caramelization: Take your time caramelizing the onions. Cooking them slowly over medium heat brings out their natural sweetness and enhances the overall flavor of the tart.
- Add Cheese for Extra Flavor: While the Gruyère cheese is optional, it adds a delightful nutty flavor that complements the tomatoes and onions beautifully.
- Serve Warm or at Room Temperature: This tart is delicious served warm, but it also tastes great at room temperature, making it perfect for picnics or potlucks.
FAQ
Can I use a different type of tomato?
Yes, you can use other varieties of tomatoes such as heirloom or Roma tomatoes. However, beefsteak tomatoes are ideal due to their size and juiciness.
Can I make this tart ahead of time?
Absolutely! You can prepare the tart a few hours ahead of time and store it in the refrigerator. Reheat it in the oven at 350°F (175°C) for about 10 minutes before serving.
What can I serve with this tart?
This tart pairs wonderfully with a simple green salad or a light soup. For a more substantial meal, consider serving it with roasted vegetables or a side of quinoa.
For more delicious tart recipes, check out our Easy Tomato Puff Pastry Tart or explore other savory dishes like the Heirloom Tomato Ricotta Tart.

Beefsteak Tomato Tart with Caramelized Onions & Thyme
Ingredients
Method
- Heat the olive oil and butter in a large skillet over medium heat. Add the thinly sliced onions and cook, stirring occasionally, until they begin to soften. Sprinkle the sugar over the onions and continue cooking, stirring frequently, until the onions are golden brown and caramelized. This process can take about 20-25 minutes. Once done, stir in the fresh thyme leaves and season with salt and pepper. Set aside to cool.
- Preheat your oven to 375°F (190°C). Roll out the thawed puff pastry on a lightly floured surface to fit your tart pan. Transfer the pastry to the tart pan, pressing it gently into the edges. Trim any excess pastry from the edges. Using a fork, prick the bottom of the pastry to prevent it from puffing up during baking.
- Spread the caramelized onions evenly over the bottom of the puff pastry. Arrange the beefsteak tomato slices on top of the onions, slightly overlapping them. Sprinkle the grated Gruyère cheese over the tomatoes, if using. Brush the edges of the pastry with the beaten egg to create a golden, glossy finish.
- Place the tart in the preheated oven and bake for 25-30 minutes, or until the pastry is golden brown and the tomatoes are tender. Remove from the oven and let it cool slightly before serving.






