Roasted onions are soft, sweet and perfect for serving alongside other roasted vegetables or meats. You can roast onions with the skins on and without any additional seasonings. That said, we add a few simple steps for making these onions extra flavorful. For serving, we love adding a drizzle of balsamic or sherry vinegar over the onions. For the best flavor, use a better-quality vinegar.
6 small to medium onions, skins left on with top and bottom trimmed
3 tablespoons (42 grams) butter, cut into 6 slabs
1/2 teaspoon fine sea salt
1/2 teaspoon cracked black pepper
1 to 2 tablespoons chopped fresh herbs like thyme, rosemary or sage
3 bay leaves
Good quality balsamic vinegar, balsamic glaze or sherry vinegar, optional, to taste
Finishing salt like Maldon flaked salt, optional, for serving
Season both the top and bottom cut ends of each onion with the salt. Arrange onions in an oven-safe baking dish. Slide the onions underneath the broiler and broil until the tops are golden brown and some of the onion skin is charred.
Turn the oven to bake and heat to 400 degrees Fahrenheit.
Remove the baking dish from the oven and place a slab of butter on top of each onion and then mound the herbs onto the butter so that when it melts, they will fall down into and over each onion. Season with pepper and scatter the bay leaves around the onions.
Cover the baking dish with foil or tuck baking parchment paper into the corners so that the dish is well covered. Bake the onions until very soft and sweet, 60 to 90 minutes. Serve as is or with a drizzle of vinegar and a pinch of finishing salt over the top.