Fry the bacon in a large heavy pot over medium heat until slightly crisp. Add the onions and cook, stirring occasionally, for 7 to 8 minutes, or until wilted and golden. Add the salt, cayenne, black pepper, and garlic and cook for about 2 minutes. Add the beer, vinegar, and molasses. Mix well.
Begin adding the greens, a third at a time, pressing down on the greens as they wilt. They will wilt considerable as they cook. Cook, uncovered, over medium heat, stirring often, for about 1 hour and 15 minutes.
Yield: 8 servings