Mary Hoover braises these collards until they're supertender and silky, but she cautions that "younger people" tend to prefer their collards crunchier. She recommends drinking the collards' cooking liquid, which she says is very healthful.
In a large pot, combine the vegetable oil, salt and sugar with 3 quarts of water and bring to a vigorous boil. Add the collards in large handfuls, allowing each batch to wilt slightly before adding more. Return to a boil. Reduce the heat and simmer the collards over moderate heat, gently turning the greens occasionally, until they are very tender, about 1 hour. Using tongs, transfer the collards to a medium bowl, drizzle with vinegar and serve.
The collards can be refrigerated in their cooking liquid for up to 4 days.