The bouillon.
Boil 10 cups water. Burn the whole fresh onions over high heat until golden brown. Add beef spareribs or ox tail into the boiling water. Skim while cooking to make a clear broth. Add browned onion and carrots after 1 hour of boiling. Cook another hour. Then remove meat and vegetable.
Strain the bouillon, season it with spices, salt, fish sause as indicated and keep boiling to server very hot soup. Add boiled water, if necessary, to have 6-8 cups of bouillon. This broth is very spicy and a little salty.
Slice tender beef finely and cooked beef coarsely. Soak dry rice noodles in hot water 10 minutes before cooking. Coolk rice noodles sparately until done (about 10-15 minutes), drain in hot water to remove the starch.
Server at once into bowl.
Beef soup, rare: cooked rice noodles 1/3 bowl, raw beef minced on top. Pour over them one cup boiling bouillon. Add bib lettuce, green onion and onion rings.
Beef soup, done: cooked rice noodles, cooked beef, bib lettuce, onion rings, green onion in top. Pour over all ingredients 1 cup boiling bouillon.
Provide the guests with spoons and chopstichs to take the soup.