In a 6-quart saucepot, sweat bacon over medium heat until golden brown, about 4 minutes.
Add onions and continue to sweat another 5 minutes.
Add chopped collards, stock and hock meat, reducing heat to low and cooking for about 45 minutes, or until the collards are extremely tender.
Stir in the sugar and vinegar and season to taste with salt and pepper.
Combine all ingredients for the stock in a 6-quart stock pot, cover with water and bring the stock to a simmer.
Continue to simmer about 3 hours, or until the ham hock is falling apart tender.
Pull the hock out, let cool briefly and then pick apart, separating the meat from the skin and bones, which can be discarded.
Strain the stock and reserve both liquid and picked meat for the collard greens.