In a large pot, saute the bacon until slightly crisp. Add the onions and season with salt, pepper and cayenne pepper. Cook 6 to 7 minutes, until the onions are wilted and golden. Add the brown sugar and stir to dissolve. Add the shallots and garlic. Cook for 2 minutes. Add the water and vinegar and mix well. Begin adding the greens, a third at a time, pressing them down as they begin to wilt. Season with salt and pepper. Reduce the heat to medium-low and cook, uncovered, until the greens are soft, about 1 hour and 15 minutes. Serve hot.