These are good old-fashioned mustard greens, cooked slow and low with a ham hock. It is a great make-ahead dish for a crowd, and it nicely rounds out a buffet. You can make the same recipe using kale or collard greens or mix up all three. Me, I prefer the strong bite of those mustard greens. I also like to substitute them for spinach in my recipe for Sautéed Spinach with Garlic Chips that you will find on page 232 of Sara Moulton Cooks at Home.
Serves 4 to 6
Remove the tough bottom stems from the greens and cut the leaves into wide strips. Pour the chicken stock into a large soup pot or kettle and bring to a boil over high heat. Add the greens and stir until wilted, about 2 minutes. Add the ham hock, reduce the heat to medium and add the pepper flakes and vinegar. Cook, partially covered, until the greens are very tender and the broth is full-flavored, about 45 minutes. Season with the sugar, salt, and pepper.
Drain the greens, reserving the cooking liquid. Rinse out the pot and pour in the strained liquid (pot likker). Transfer the hock to a bowl and cool. When the hock has cooled, remove the skin, fat, and gristle. Cut the resulting lean ham into small pieces. Bring the liquid (about 2 cups) in the pot to a boil over high heat. Boil until reduced by half. Reduce the heat to medium and return the greens to the pot. Season with salt and pepper and stir until warmed through, about 3 minutes. Turn out into a warmed serving bowl and garnish with the pieces of ham. Serve hot.