Rinse the beef bones thoroughly with vinegar to remove any odor. Next, place the bones in a pot of water with a pinch of salt. Bring to a boil to release impurities, then turn off the heat and rinse the bones clean.
- Lightly crush the ginger and lemongrass, then add them to a pot with about 8–12 cups water (2–3 liters). Add the beef bones and simmer until the bones are tender.

Add 3 tablespoons fish sauce, 2 tablespoons salt, 2 tablespoons sugar, 2 tablespoons MSG, and a small bowl of fermented shrimp paste mixed with a little water (about 2–3 tablespoons shrimp paste).
- To make the broth more flavorful, prepare annatto oil: sauté 1 tablespoon minced lemongrass and 1 tablespoon minced garlic with 1 tablespoon minced chili in oil. Add 2–3 tablespoons annatto oil. Pour all the annatto oil mixture into the simmering broth, add chopped green onions, and adjust seasoning to taste.