Onion Tarte Tatin
This Onion Tarte Tatin turns humble yellow onions into a glossy, jammy, golden tart that looks like it came straight out of a French bistro. It is the savory cousin of the classic apple tarte tatin, with sweet balsamic caramel hiding under a crown of flaky puff pastry. Everything happens in one skillet, and the oven does most of the work, making it an easy yet impressive dish that works as an appetizer, side dish, or light vegetarian main.
Equipment
- 10-inch cast iron skillet or other heavy oven safe skillet
- Sharp chef's knife
- Cutting board
- Rolling Pin
- Tongs or a small spatula for arranging the onions
- Fork for pricking the pastry
- Silicone oven mitts for flipping the hot skillet
- Large serving plate or platter slightly wider than the skillet
- Rimmed baking sheet to catch any bubbling caramel
- Lid or foil for covering the skillet
- Small bowl or plate as a guide for cutting the pastry round
Ingredients
- 1 1/2 pounds small yellow onions about 6 onions or 680g, peeled and halved through the root end
- 3 tablespoons unsalted butter about 42g
- 2 tablespoons granulated sugar about 25g
- 2 tablespoons balsamic vinegar about 30ml, preferably a syrupy aged balsamic
- 1 tablespoon fresh thyme leaves plus a few extra sprigs for garnish
- 1/2 teaspoon kosher salt
- 1/4 teaspoon freshly ground black pepper
- 2 tablespoons water about 30ml
- 1 sheet puff pastry about 9 to 10 ounces or 255-285g, thawed
- all purpose flour for dusting the work surface
- 3 ounces goat cheese about 85g, crumbled, for serving
- flaky sea salt for finishing
Instructions
- Place an oven rack in the center position and preheat the oven to 400°F (200°C). Thaw the puff pastry in the refrigerator according to package directions so it stays cold but is easy to unfold.
- Peel the onions and trim off the tops, leaving the root ends attached. Cut each onion in half from top to root to get 12 neat halves, and discard any loose outer layers that could burn.
- Set a 10 inch oven safe skillet over medium heat and melt the butter. When it foams, sprinkle the sugar evenly over the bottom and cook for 2 to 3 minutes without stirring, swirling gently, until light amber.
- Carefully pour in the balsamic vinegar, which will bubble up quickly, and stir for about 30 seconds until glossy. Stir in the thyme, kosher salt, and black pepper, then remove the pan from the heat for a moment.
- Place the onion halves cut side down in the caramel, starting at the outer edge and working toward the center. Pack them tightly and tuck in small wedges to fill any holes so the base looks like a mosaic.
- Return the skillet to medium heat and cook the onions uncovered for about 10 minutes without moving them, until the cut sides turn deep golden brown.
- Add the water around the edges of the pan, cover tightly with a lid or foil, and reduce the heat to medium low. Steam for 8 to 10 minutes until a knife slides easily into the thickest part of an onion.
- Remove the lid and cook for 2 to 3 more minutes until most of the liquid reduces to a thick, syrupy caramel. Take the skillet off the heat and let it cool for about 5 minutes.
- Lightly dust a clean work surface with flour, unfold the pastry, and gently roll it into an 11 inch square. Cut out an 11 inch round and prick it all over with a fork so steam can escape.
- Lay the pastry round gently over the warm onions, tucking the edges down the inside of the skillet with a spoon or your fingertips. Press lightly so the pastry touches the onions with no big air pockets.
- Place the skillet on a rimmed baking sheet and bake in the center of the oven for 25 to 30 minutes, until the pastry is puffed, deeply golden, and crisp with thick caramel bubbling around the edges.
- Remove the skillet from the oven and let the tart rest for 10 minutes so the caramel thickens slightly and does not run everywhere when you flip it.
- Run a thin knife around the inside edge of the skillet to loosen any stuck caramel. Place a large serving plate upside down over the skillet, hold both firmly with oven mitts, and flip in one quick, confident motion.
- Lift the skillet away slowly and nudge any onions that stayed behind back into place. Scatter the crumbled goat cheese over the top, add fresh thyme sprigs, and finish with flaky sea salt. Slice into 6 wedges and serve warm.
Notes
- Pack the onions tightly in the skillet: they shrink as they cook, and a tight arrangement keeps the tart together when you flip it.
- Watch the caramel color and stop the sugar at light amber, because it keeps darkening once the onions go in.
- Keep the pastry cold: cold pastry puffs higher and bakes crispier, so chill it briefly if it feels soft or sticky.
- Do not skip the fork pricks, as they let steam escape so the pastry does not balloon and lift off the onions.
- Rest the tart for 10 minutes before flipping: the caramel thickens but does not harden onto the pan.
- Flip with confidence: a slow, hesitant flip is the main reason onions slide off, so commit to one quick motion.
- Make ahead: cook the onions and caramel up to a day ahead, cover the skillet, and refrigerate, then add the pastry and bake just before serving.
- Store leftovers in an airtight glass container in the refrigerator for up to 3 days and reheat on a baking sheet in a 350°F oven for 10 to 12 minutes; avoid the microwave, which makes the pastry chewy.
- Freezing the baked tart is not recommended because the texture of both the onions and the pastry suffers.
- Variations: swap in shallots, red onions, or leeks; sprinkle 1/2 cup grated Gruyère over the onions before adding the pastry; add chopped rosemary or sage with the thyme; or replace one tablespoon of balsamic with dry sherry or port for a richer caramel.
Nutrition
Serving: 1SliceCalories: 290kcalCarbohydrates: 29gProtein: 5gFat: 18gSaturated Fat: 8gSodium: 330mgFiber: 2gSugar: 11g
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