Caramelized Onion Tart Tarte A Loignon Alsacienne Recipe

This Tarte à l’Oignon Alsacienne is my absolute go-to for hosting friends because it’s the perfect blend of comfort and sophistication. The caramelized onions paired with the creamy Gruyère are like a warm hug, and honestly, who doesn’t love anything with puff pastry?

A Caramelized Onion Tart combines the savory, rich flavors of perfectly golden onions, sautéed in a buttery blend of olive oil and a touch of sugar. If there was ever a reason to engorge yourself with onions, this tart is it.

I dare say it might even get my sister, who abhors the very thought of consuming an onion, to give in to this allium advocacy.

Caramelized Onion Tart Tarte A Loignon Alsacienne Recipe Ingredients

• Onions: Rich in antioxidants, promote heart health, mild sweetness when caramelized.
• Puff Pastry: Buttery, flaky texture, high in carbohydrates, adds decadent layers.
• Gruyère Cheese: Provides protein and calcium, nutty flavor, creamy texture when melted.
• Crème Fraîche: Rich and tangy, adds creaminess, contains beneficial probiotics.
• Eggs: High-quality protein, essential vitamins, help bind tart ingredients.
• Olive Oil: Healthy monounsaturated fats, enhances flavors, supports heart health.
• Thyme: Aromatic herb, adds earthiness, potential anti-inflammatory properties.

Caramelized Onion Tart Tarte A Loignon Alsacienne Recipe Ingredient Quantities

• 1 sheet of puff pastry, thawed
• 4 large onions, thinly sliced
• 2 tablespoons butter
• 1 tablespoon olive oil
• 1 teaspoon sugar
• Salt and freshly ground black pepper, to taste
• 3/4 cup crème fraîche or heavy cream
• 2 large eggs
• 1/2 teaspoon ground nutmeg
• 1/2 cup grated Gruyère or Swiss cheese
• 2 tablespoons fresh thyme leaves, optional

How to Make this Caramelized Onion Tart Tarte A Loignon Alsacienne Recipe

1. Your oven should be set to 400°F (200°C) for preheating. On a surface dusted with flour, roll out the sheet of puff pastry and fit it into a tart pan, trimming the edges as needed. Chill the pastry in the fridge after pricking the base all over with a fork.

2. In a vast frying pan, combine the butter and olive oil, and heat them until medium over the stovetop. Throw in the onions, which you’ve cut into even slices, along with a couple of pinches of salt. The salt helps the onions give off their moisture. You want the onions to cook low and slow, and the salted onions in the covered pan allow that to happen.

3. Add salt and freshly ground black pepper to taste to the caramelized onions. Take the onions off the heat and let them cool down a little.

4. In a mixing bowl, combine the crème fraîche (or heavy cream), eggs, and ground nutmeg. Whisk until smooth.

5. Evenly distribute the cooled, caramelized onions over the pastry base in the tart pan that you have prepared.

6. Distribute equally over the onions the mixture of crème fraîche and eggs.

7. Grate and evenly distribute the Gruyère or Swiss cheese over the top of the tart.

8. If you are using fresh thyme leaves, scatter them over the entire tart for added flavor.

9. Place the tart in the oven that has been preheated to the required temperature. Allow it to cook for 30 to 35 minutes, watching carefully, as always, to ensure it does not overbake. You want the filling to be well set and the top to be a lovely golden brown.

10. Let the tart cool a little before cutting it and serving it warm. Enjoy your Tarte à l’Oignon Alsacienne!

Caramelized Onion Tart Tarte A Loignon Alsacienne Recipe Equipment Needed

1. Oven
2. Tart pan
3. Rolling pin
4. Knife
5. Fork
6. Frying pan
7. Wooden spoon or spatula
8. Mixing bowl
9. Whisk
10. Cheese grater

FAQ

• What kind of onions should I use for the tart?Employ yellow onions, which caramelize well, develop a sweet flavor, and have a rich taste.
• Can I make the tart in advance?You can make the tart hours in advance and warm it in the oven before you serve it.

  This would be an excellent dish to prepare for a brunch, where you can somewhat guarantee that everyone will be filling their plates in a specific hour (as opposed to dinner, where plate-filling times can be more staggered).

• What if I don’t have Gruyère cheese?Swiss cheese, or even a mild cheddar, can be used in place of Gruyère.
• How can I ensure the onions caramelize properly?SLOWLY COOK THE ONIONS. Combine equal parts (1 tablespoon each) of
  butter and olive oil in a large sauté pan over medium-low heat. Add the
  sliced onions, sprinkle with a little (1/2 teaspoon) sugar, and season with
  salt and pepper.
• Is there an alternative to crème fraîche?Certainly, heavy cream or even sour cream can work well as substitutes.
• Can I make this tart gluten-free?Substitute the regular puff pastry with a gluten-free puff pastry.
• What is the best way to thaw puff pastry?Retrieve puff pastry from cold storage. Thaw it in the fridge for several hours or overnight, yielding the best results. When making (insert pastry name), it is imperative that puff pastry be properly thawed.

Caramelized Onion Tart Tarte A Loignon Alsacienne Recipe Substitutions and Variations

Substituting puff pastry with a different type of crust will yield a different texture. You can use homemade pastry crust or store-bought pie crust in place of puff pastry.
Substitute shallots for onions when you want the flavor to be less intense and a hair closer to sweet. Basically, using shallots instead of onions makes your dish taste more nuanced. Why? Because shallots have a better balance of sweetness and savory flavor.
If needed, substitute an equal amount of vegetable oil or canola oil for the olive oil.
In the absence of crème fraîche, use sour cream or plain Greek yogurt.
Use Emmental or Comté for a similar taste instead of Gruyère cheese.

Pro Tips

1. Caramelize with Care Take your time caramelizing the onions. Low and slow is key here; it can take up to 30-40 minutes to achieve a deep, rich caramelization. Stir occasionally to ensure even cooking and prevent them from browning too quickly or burning.

2. Chill the Pastry After fitting the pastry into the tart pan and trimming the edges, chill it in the fridge for at least 20-30 minutes before baking. This helps prevent the pastry from shrinking and ensures a crisp base.

3. Blind Baking Consider blind baking the puff pastry shell. Place parchment paper over the crust and fill it with baking weights or dried beans. Bake for about 10-12 minutes, then remove the weights and continue baking for another 5 minutes. This extra step can help the pastry base stay crisp even with the wet filling.

4. Strain Excess Liquid After caramelizing the onions and letting them cool, strain any excess liquid that may have accumulated. This helps prevent a soggy tart.

5. Flavor Enhancements For added depth of flavor, try incorporating a splash of white wine or balsamic vinegar towards the end of the onion caramelization process. This adds a subtle acidity and enhances the overall taste.