Put the oxtail with enough cold water to cover completely in an 8-quart stockpot. Bring the liquid to a gentle boil and cook for about 5 minutes. Drain and discard the liquid. Rinse the oxtail under cold running water to remove any scum from parboiling.

Return the oxtail to the pot, add the rest of the ingredients and 4 quarts water, and slowly bring to a simmer over low heat. Skim off any scum that forms on top of the liquid. Simmer uncovered for 2 hours.

There is no need to season the stock since the hot pot is served with dipping sauces. Put about one third of the oxtail stock, along with a few pieces of the oxtail, in the hot pot at the beginning, then replenish as the meal progresses.