Preheat the oven to 425 degrees F.
Toss the carrots in the oil and the salt and place them in a shallow roasting pan. Roast in the middle of the oven, stirring from time to time, until they turn a beautiful golden color and become tender. This should take about a half hour.
Drizzle the vinegar over the carrots and shake the pan a few times.
Roast the carrots until most of the vinegar is evaporated, which should take approximately five minutes more.