Ingredients
1 Parmesan rind (3 to 4 inches long)
3 pounds (about 4 bunches) collard greens, stalks removed, leaves cut into 1-inch pieces
Pinch red-pepper flakes, or more to taste
3 tablespoons white-wine vinegar
Kosher salt and freshly ground pepper
Hot sauce, for serving (optional)
Preparation
In a large pot, combine Parmesan rind, collard greens, red-pepper flakes, and 8 cups water; bring to a boil. Reduce to a simmer, and cook until collards are very tender, 45 minutes to 1 hour.
Remove Parmesan rind, and discard. Add vinegar, and season with salt and pepper. Serve collards with their broth, and, if desired, hot sauce.
