Can I make the caramelized onions ahead of time?

Absolutely! The onions can be caramelized up to 3 days ahead and stored in the refrigerator. They also freeze beautifully for up to 3 months, making these tarts even quicker to put together when the craving strikes.

Why didn't my puff pastry rise properly around the edges?

The most common reason is that the pastry wasn't cold enough when it went into the oven. Puff pastry relies on cold butter creating steam to separate the layers. If your kitchen is warm, pop the prepared tarts in the refrigerator for 10-15 minutes before baking.

Can I use yellow onions instead of the large onions called for?

Yes! Any type of onion works for caramelizing - yellow, white, red, or sweet onions. Each will give a slightly different flavor profile, but all caramelize beautifully. Sweet onions like Vidalias will caramelize faster and give a more intense sweetness.

How can I make these tarts gluten-free?

Look for gluten-free puff pastry at specialty stores or online. While the texture isn't identical to traditional puff pastry, there are increasingly good options available. The filling is naturally gluten-free, so only the pastry needs substitution.

Caramelized Onion Tarts Recipe

Description

These Caramelized Onion Tarts are a delightful combination of flaky puff pastry, sweet caramelized onions, and tangy feta cheese. Perfect as an appetizer or a snack, they are easy to make, and you can choose to use homemade or store-bought puff pastry. Served warm or at room temperature, they are sure to be a crowd-pleaser at any gathering or occasion.

Ingredients

Units Scale

Puff Pastry and Filling

1/2 batch rough puff pastry or classic puff pastry (or store-bought, see notes)
3 large onions, sliced thin
2 tablespoons olive oil
1/4 teaspoon salt
1 tablespoon balsamic vinegar
3 ounces crumbled feta (about 3/4 cup)
Egg wash (1 egg whisked with 1 teaspoon of water)
1 small bunch of chives, sliced fine

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Instructions

Prepare the Puff Pastry:
Prepare your puff pastry by making half a batch if you’re using homemade, or defrost the store-bought puff pastry as per package instructions. If you’re making it yourself, you can freeze the other half for another use. Roll out the pastry to about an ⅛” thickness, forming a 10” by 14” rectangle.
Caramelize the Onions:
Heat olive oil in a wide, heavy-bottomed pan over medium heat. Add the sliced onions and cook for about 10 minutes, stirring occasionally to ensure they start to soften and get evenly cooked. Add a pinch of salt, lower the heat to medium-low, and let the onions sit undisturbed for 20 minutes. Continue cooking for another 15 minutes, stirring every 5 minutes to prevent burning. Stir in the balsamic vinegar and cook for an additional 5 minutes, or until the onions have caramelized to your liking. Let them cool to room temperature.
Mix Onions and Feta:
In a small bowl, mix the cooled caramelized onions with the crumbled feta cheese. Set the mixture aside.
Cut the Puff Pastry:
Using a 3-inch circle cutter, stamp out at least 12 pastry circles from the rolled-out pastry. Use a 2-inch cutter to gently indent a smaller circle within each pastry cut-out, being careful not to cut through the pastry completely. Dock the center of each circle with a fork to prevent it from puffing too much during baking.
Assemble the Tarts:
Line a 13×18” sheet pan with parchment paper and preheat the oven to 400ºF. Place the cut pastry circles evenly spaced on the prepared baking sheet. Brush the outer edges of each pastry with egg wash. Add a heaping tablespoon of the onion and feta mixture to the center of each tart.
Bake the Tarts:
Bake the tarts on the middle rack of the oven for 15-18 minutes, or until the puff pastry is golden brown and puffed up.
Garnish and Serve:
Remove the tarts from the oven and let them cool slightly before transferring them to a cooling rack. Sprinkle sliced chives over each tart before serving. Enjoy warm or at room temperature.

Notes

Homemade puff pastry provides superior flavor and texture compared to store-bought, but either option works depending on your time and preference.
Leftover caramelized onions can be stored in the refrigerator for a few days or frozen for a few months.
You can customize the tart size based on the size of your cutter. Baking time may vary slightly depending on tart size.
For the best taste, serve these tarts on the same day they are made. They can also be reheated if stored properly.
Tarts can be frozen and reheated directly from frozen, though they’ll taste best fresh.

Nutrition

Serving Size: 1 tart
Calories: 180
Sugar: 4g
Sodium: 250mg
Fat: 12g
Saturated Fat: 5g
Unsaturated Fat: 7g
Trans Fat: 0g
Carbohydrates: 15g
Fiber: 1g
Protein: 4g
Cholesterol: 25mg