I always come back to this red onion tart recipe when I want a simple, rustic and frankly satisfying dish.
I remade and adjusted it several times to find the right balance: really melting onions (not just “sautéed”), a well-cooked base, and a filling that is just creamy enough to bind without turning the tart into a quiche.
The heart of the onion tart recipe is the compote. I take my time: I sweat the onions gently, let them caramelize slightly, then deglaze with balsamic vinegar.
It brings out their sweet side and gives them that little "come back for more" flavor without being overpowering. Then the thyme comes in, like a nod to Southern tarts.
As for texture, I pre-bake the pastry for a few minutes. This prevents a soggy base (the classic pitfall).
Next, the egg and cream mixture comes to the rescue: it coats and sets the sauce, but it lets the onions remain the stars. And with a small green salad, you have a perfect dinner!
Nutritionally, it's quite nice: the onions provide fiber and antioxidants, and you can adjust the amount of cream to your liking. If you like, a touch of mustard on the bottom of the tart before the onions is my little "home-cooked" trick to boost the flavor without making things complicated.
Red onion tart
4
people23
minutes32
minutes519
kcal55
minutesA savory tart recipe , featuring red onions slowly simmered until meltingly soft and slightly sweet. All this in a crisp pastry shell, with a touch of thyme and a dollop of cream. Yum!
Keep your device's screen on
Ingredients
1 shortcrust pastry (approximately 230g each)
650g of red onions
2 tablespoons of olive oil (approximately 15ml per tablespoon)
20g of butter
1 tablespoon of balsamic vinegar (15ml per tablespoon)
1 teaspoon of thyme (fresh or dried)
2 eggs
20 cl of full-fat fresh cream
1 teaspoon of Dijon mustard (optional but classic)
1/2 teaspoon of fine salt
Black pepper
Preparation steps
- Preheat the oven to 200°C (fan oven if possible).
- Peel the red onions, then slice them into thin strips.
- In a large frying pan, heat the olive oil and butter. Add the onions, salt, and a grind of pepper. Sauté them over medium heat for 6 to 8 minutes, stirring occasionally; they should become soft but not burnt.
- Lower the heat and let it simmer for 10 to 12 minutes. Stir regularly: the goal is a soft consistency with a light colouring.
- Deglaze with the balsamic vinegar, scraping the bottom of the pan well and let it reduce for 1 minute. Add the thyme, stir, then turn off the heat.
- Line a tart tin (24–26cm) with the shortcrust pastry. Prick the base with a fork.
- Pre-bake the dough for 8 minutes in the oven. Take it out (without turning off the oven).
- If using, spread the mustard in a thin layer on the pre-baked pie crust.
- Spread the red onion compote over the dough.
- In a bowl, beat the eggs with the cream. Add pepper. Taste and adjust the salt slightly (the onions are already salty).
- Pour the mixture over the onions, without completely drowning them: it should just slip between the slices.
- Bake for 24 minutes, until the tart is golden brown and the center is set (it should barely jiggle). Let it rest for 5 minutes before cutting.
📊 Nutritional Information
1 serving (approx. 235g)
| Nutrient | Value |
|---|---|
| Calories | 519 kcal |
| Proteins | 9g |
| Carbohydrates | 45g |
| including sugars | 11g |
| Lipids | 35g |
| including saturated fatty acids | 16g |
| Fibers | 5g |
| Sodium | 520mg |
| Vitamins | |
| Vitamin A | 15% AJR |
| Vitamin B9 | 18% AJR |
| Vitamin C | 16% AJR |
| Minerals | |
| Potassium | 18% AJR |
| Phosphorus | 16% AJR |
| Iron | 12% AJR |
* RDA = Recommended Daily Allowance
📝 Notes
If you serve it warm, the flavors come through even better. And the next day, reheated for 8 to 10 minutes at 170°C, it will become nice and crispy again!
💡 Chef's Tips
To avoid a soggy base, pre-cooking is your best friend. If the red onions used for the tart are browning too quickly, lower the heat and add 1 to 2 tablespoons of water: this will help them cook down without burning.
🔄 Variations
- For a more rustic recipe: replace the shortcrust pastry with puff pastry.
- For a more robust red onion tart: add 1 pinch of nutmeg to the egg-cream mixture.
