Place ham hocks, salt pork, onion, bay leaves, red pepper flakes, and sugar in a large pot with the chicken stock. Bring to a boil, reduce heat to simmer, and cook for 30 minutes.
Stir collard greens into the pot, and bring to a boil. Reduce heat to simmer, and cook for 30 minutes, or until greens are tender. Season with red wine vinegar and salt and pepper to taste.
