Onion Confit Recipe: How to Make Confit d'Oignon

Onion confit, also known as confit d'oignon, is a dish of slow-roasted onions in olive oil with aromatics like garlic and fresh herbs, softened over a few hours in a low-heat oven. “Confit” is a French term that refers to an ingredient preserved in fat—either its own, as with duck confit, or in olive oil, like garlic confit. Making onion confit both extends the life of fresh onions and deepens their innate sweetness, resulting in a complex flavor profile that suits several uses.

Consider these tips for making and storing onion confit:

1. 1. Add sugar for extra complexity. To enhance the natural sugars in the onions, add a teaspoon of brown sugar or balsamic vinegar to the oil mixture. The low-and-slow cooking process gives the sugar time to develop a deep, caramel flavor, while the tanginess of the balsamic will mellow into an earthy fruitiness.
2. 2. Cut the onions. You can use small onions, like pearl onions, or larger varieties, like red or yellow onions, to make confit. If using larger onions, cut them into halves or thick wedges, and place them cut-side down in the baking dish.
3. 3. Keep leftover onion confit. Store onion confit in an airtight container in the refrigerator, where it will last for up to one month. Or blend the onions and some of the infused oil to make a spreadable onion jam perfect for grilled cheese sandwiches.

There are several ways to serve onion confit with appetizers and side dishes. Consider the following culinary applications:

1. 1. As a topping: Serve onion confit over pasta as a minimalist sauce (garnished with plenty of grated Parmesan cheese), or spoon it over grilled fish or roasted chicken.
2. 2. In salads: Use it as a stand-in for fresh onions in a composed salad like a caprese, with torn mozzarella or burrata, or drizzled with fresh pesto and a pinch of flaky sea salt.
3. 3. With cheese: Serve onion confit with a charcuterie board as a spread for soft cheeses like ricotta or goat cheese.
4. 4. With toasted bread: Serve onion confit with thick slices of grilled bread or crispy, thin crostini, either on its own, drizzled in aged balsamic, or as part of bruschetta with fresh basil.