Balsamic Roasted Red Onions

I consider the onion, the workhorse of my home kitchen. It’s an indispensable ingredient, but rarely does it take center stage.

There are exceptions, of course, like French onion soup, or these Greek rice-stuffed onions. One of my favorite ways to showcase onions is to give them the agrodolce treatment, a classic Italian preparation that mixes sweet and savory flavors for a knock-out delivery.

Typically, agrodolce onions are made with pearl or cipollini onions, sautéed on the stovetop. They’re delicious, but peeling those tiny onions is tedious. Here, I roast quartered red onions instead, then toss them with balsamic vinaigrette while they’re still warm.

The bright flavor of the red onions pairs perfectly with the sweet-tart vinaigrette. It’s a simple preparation but the results will delight you, I promise! 

How to Make Roasted Red Onions

These baked onions are practically a foolproof side dish. The key is to roast the onions until they are nicely caramelized and silky but still have a little bite to them. You can prepare the vinaigrette while the onions are in the oven.

• Get ready. Heat the oven to 400° F. Line a rimmed baking sheet with foil. 
• Prep the onions. Trim the ends off 6 medium red onions, peel, then cut them into quarters. Arrange on the prepared baking sheet and drizzle with 2 tablespoons extra virgin olive oil. Use your fingers to coat them and season with a pinch of salt and freshly ground black pepper. Roast for 15 minutes.
• Make the vinaigrette. In a small bowl, combine 1 tablespoon apple cider vinegar, 1 tablespoon balsamic vinegar, 1/4 teaspoon salt, 1/8 teaspoon pepper, and 1/2 teaspoon finely chopped fresh thyme leaves. Slowly whisk in 1/4 cup olive oil, until the vinaigrette is emulsified.
• Baste the onions. Remove the pan from the oven and brush the onions with about half the vinaigrette, turning them to make sure all sides are coated. Return the onions to the oven and roast until the wedges are nicely caramelized and slightly blackened in spots, another 15 to 20 minutes.
• Finish and serve. Gently transfer the onions into a bowl. Don’t worry if they fall apart a little. Drizzle the remaining vinaigrette over them and toss gently with a spoon. Taste and adjust the seasoning with more salt or pepper if needed. Let the onions marinate for about 15 minutes before serving.

What is Agrodolce?

Mixing sweet and tart flavors is a hallmark of Italian cuisine. Agrodolce sauce is typically made from a mix of vinegar and sugar or honey or another sweet ingredient such as balsamic vinegar.

Sometimes the mixture is reduced on the stovetop to thicken it. For this recipe, the sweet and tart elements come together in a vinaigrette, no reduction needed! 

I use two vinegars to make this vinaigrette—cider vinegar, which has a fresh kick, and balsamic vinegar, which is sweet and syrupy. Together, they have just the right amount of agrodolce.