Roasted Onions Agrodolce

Heat the oven to 450°F and arrange a rack in the middle.

Combine onions, bacon, and olive oil in a 13-by-9-inch baking dish, stir to coat onions in oil, season with salt and freshly ground black pepper, and place in the oven.Roast, stirring occasionally, until onions are golden and start to become tender, about 30 minutes. Meanwhile, combine remaining ingredients in a small saucepan over medium heat, stir until sugar is dissolved, then continue cooking until reduced by 1/2, about 20 minutes.When onions are done, remove from the oven, pour sauce over them, reduce oven temperature to 400°F, and return the baking dish to the oven. Roast onions, basting occasionally, until sauce is thick and syrupy, about another 8 minutes.

Remove from the oven and stir onions to coat in sauce. Return to the oven and continue roasting until fork tender, about 8 minutes more.

Serve hot or lukewarm.