Bun Bo Hue is a comforting Vietnamese noodle soup known for its bold and spicy broth, a hearty and satisfying dish with complex, robust flavors, so good.
Add the beef shank and pork hocks to a pot. Cover with water and a bit of salt, then boil them. Drain and rinse. Rinse the pot, return the bones, then add the beef brisket, onion, lemongrass, garlic, ginger, and salt. Add enough water to cover, bring to a boil then simmer, skimming any foam that rises to the surface.
Remove the brisket and pork hocks and cool them down enough to handle. Thinly slice the brisket and pick out the pork meat. Toss the pork bones and refrigerate the meat for now.
Simmer the stock to let the flavors develop further. Add water as needed. Also, skim off any fat and scum that rises to the surface as you simmer.
Remove from heat. Pick any remaining meat from the bones and discard the beef bones but reserve the meat.
Process the chili flakes or fresh chilies, ground annatto, shrimp paste, shallot and garlic in a food processor to form a paste. Cook the paste in a small pan with oil until the mixture becomes aromatic.
Stir the cooked paste into the stock along with salt and sugar, then simmerto let the flavors develop and mingle. Cook the noodles and distribute between the serving bowls along with the reserved meats. Ladle in the seasoned hot broth and serve with garnishes. Drizzle with spicy chili oil, if desired.