Meanwhile, increase the oven temperature to 400°. Spoon 1 tablespoon of the confit oil into a medium saucepan. Add the onion and carrot and cook over moderate heat, stirring occasionally, until softened, about 7 minutes. Add the couscous and stir to coat with oil. Add the water and a generous pinch of salt and bring to a boil. Cover and remove from the heat. Let stand until the couscous is tender and plumped, about 10 minutes. Fluff with a fork, cover and keep warm.