Roasted Vegetable Sauce

Preheat an oven to 400°F.

In a large bowl, stir together the onions, parsnips, carrots, potatoes, garlic, thyme and olive oil. Transfer the vegetables to a large roasting pan and spread evenly.

If roasting the vegetables with a turkey, place a roasting rack over the vegetables and set the turkey on the rack. Roast according to your turkey recipe.

If roasting the vegetables on their own, cover the pan with aluminum foil and roast, stirring the vegetables occasionally, for 1 1⁄2 hours. Uncover the pan and continue to roast until the vegetables are fork-tender and lightly caramelized, 15 to 30 minutes more. If the vegetables start to dry out, re-cover the pan with foil.

Set the roasting pan on the stovetop. If you roasted a turkey, transfer the turkey to a carving board and remove the rack from the pan. Pour any excess fat into a gravy separator. Pour 2 cups broth into the pan and turn on the stove to medium heat. Using a wooden spoon, stir to scrape up the browned bits. Pour the liquid into the gravy separator. Fit a food mill with a fine disk and set over a large bowl. Transfer the vegetables to the mill and process into a smooth puree.

Transfer 2 cups of the pureed vegetables to a saucepan; discard the remaining puree. Pour the liquid from the gravy separator into the pan along with the remaining 2 cups broth. Set over medium-high heat and bring the mixture to a simmer, whisking often. Simmer until the sauce begins to thicken, 3 to 5 minutes. Stir in the sherry and season with salt and pepper. For a smoother texture, pour the sauce through a fine-mesh strainer, pressing it through with the back of a ladle. If desired, simmer the sauce to reach the desired thickness. Pour the sauce into a warmed sauceboat and serve with the turkey. Makes about 4 cups.