Place all beef, including brisket, in a large stockpot. Bring to a boil for 5 to 10 minutes and then strain. Rinse and place blanched pieces back into the cleaned stock pot. Fill the pot with enough water to cover bones and have about an inch or two extra. Will be about 15 cups.
Place onion, ginger and garlic, cut sides up, on a cookie sheet and broil in the oven for about 5 minutes, until they start to char slightly. Add to the stockpot with blanched meat pieces along with the peppercorns.
Cover stockpot and simmer for 3 hours, when checking, if you see foam on top skim. Remove brisket, let cool and refrigerate until needed. Continue cooking remaining bones and spices for another 3 to 4 hours.
Using tongs, remove as many bones and spices as possible and then strain remaining broth into a large measuring bowl. Add broth back to the stock pot and add the remaining ingredients: sugar, salt and fish sauce. Set heat on low and stir broth well for about 5 minutes.