Caramelized Onion Tart (Tarte à l’Oignon Alsacienne)
With its buttery, crisp crust and a rich filling of sweet caramelized onions in a savory custard, this Caramelized Onion Tart is a cherished gem from the Alsace region. This rustic and comforting dish delivers a delightful balance of sweet and salty flavors, and is perfect as an elegant appetizer, a light lunch, or a satisfying dinner. Indulge in the timeless charm of this Eastern French classic! What is a Caramelized Onion Tart (Tarte à l’Oignon Alsacienne)? This French Onion Tart, known as “Tarte à l’Oignon” or “Zwiebelkueche”, is a…
- Prep time
- 20 min
- Cook time
- 2 hr
- Yield
- 8 servings
- Difficulty
- HARD
Ingredients
Quantities are shown as originally provided.
- For the pie crust:
- 2 cups (260g) all-purpose flour
- 1 tsp salt
- 2/3 cup (150g) cold unsalted butter, cut into small cubes
- 4 tbsp (60ml) ice cold water
- For the filling:
- 3.3 lbs (1.5 kg) onions
- 1/2 cup (115g) unsalted butter
- 2/3 cup (158ml) white wine
- ½ cup (125ml) whole milk (whole or 2% m.f)½ cup (125ml) heavy cream
- 3 large eggs, at room temperature 1 tsp caraway seeds
- ¼ tsp salt
- ¼ tsp black pepper
- 1/2 cup (50g) Gruyère cheese, grated
Instructions
- 1
Make the crust. Mix the flour, salt and butter with your fingers or pulse in a food processor, until you get a crumbly consistency and pea-size bits of butter are still visible. Add the water, one tablespoon at a time, and mix until the dough roughly comes together into a ball; do not overmix. Add a few more splashes of water if you feel the dough is too crumbly/dry. Wrap the dough in plastic wrap and chill for at least 30 minutes.
- 2
Pre-heat your oven to 350°F (180°C) with a rack in the middle.
- 3
Line with parchment paper a 9-inch (22.9 cm) or 10-inch (25,4 cm) pan. Transfer the dough onto a floured working surface and roll it out to a 12-inch (31cm) circle. Transfer the crust to the prepared tart pan. Cut any excess crust that hangs over the edges and crimp the edges (optional). Poke the bottom of the crust all over with a fork. Line the top of the crust with foil or parchment paper and place pie weights or dried beans over top, to keep the pie crust from puffing when baking.
- 4
Bake the crust for 15 minutes. Carefully remove the parchment paper filled with weights and set the crust aside.
- 5
Caramelize the onions. Melt the butter in a large frying pan over medium-low heat. When the butter is sizzling, add the onions slices and stir to coat with the butter. Using a spatula or wooden spoon, spread the onions evenly onto the pan. Let the onions cook for 15 minutes, stirring every 5 minutes. After 15 minutes, when the onions should start to dry out, add the white wine. Stir to coat and continue cooking for about 30 more minutes, until the onions are melty and golden. Set aside.
- 6
Make the filling. In a large mixing bowl, whisk together the eggs, the heavy cream and the milk. Add caraway, salt, black pepper and grated cheese.
- 7
Assemble the tart. Scatter the caramelized onions evenly onto the bottom of the pre-baked crust. Pour the prepared liquid filling over top.
- 8
Bake for 1 hour at 350°F (180°C) , or until golden. The middle will be slightly wobbly and puffy, and will firm up and deflate as it cools down. Transfer onto a cooling rack and let cool at least 15 minutes before serving. Enjoy it warm or at room temperature.