Most butchers carry beef shank, but short ribs are a good substitute.
Combine all ingredients in a 4-quart stockpot and bring to a boil. Reduce heat and simmer, uncovered, for 2 hours, skimming foam as it rises to the top.
Let cool slightly and strain. Remove meat from bones; discard bones and vegetables. Shred meat into small pieces and reserve. Refrigerate stock, overnight if possible, and remove hardened fat with a spoon.