Combine vinegar and chilies; set aside.
Place soup bones in a large roasting pan and roast for 25 minutes at 400° F. Transfer to a large soup kettle and cover with water. Bring to a boil, lower heat to medium-high and cook, uncovered, for 30 minutes. Skim off any foam that collects while cooking; discard.
Add beef chuck, onion, spices and salt. Add more water to cover, if necessary, and bring to a boil once again. Reduce heat to medium and simmer, covered, for 1½ hours.
Remove pieces of beef to a plate. Allow to cool and thinly slice; place in the refrigerator.
Continue boiling broth with bones, uncovered, at medium heat for another 1½ hours. Remove from heat and strain through a fine-mesh colander or cheesecloth. Discard solids.
Stir in fish sauce and ¾ of the green onions, keeping broth over low heat.
Prepare noodles according to package directions. Once soft, drain and place in room temperature water until read to serve.
To serve, place a pile of noodles into each individual bowl. Top with slices of beef, green onions and cilantro. Ladle hot broth over all and season with the vinegar and chile sauce. Salt to taste and add a grind of white pepper.