Rinse the pork hock and beef thoroughly.

Finely chop half the lemongrass, the onion, garlic, and chili pepper.

Heat some cooking oil in a pan. Add 1 tablespoon annatto seeds and stir until the oil turns a nice color, then remove the seeds. Add the chopped onion, garlic, chili, and lemongrass to the oil and sauté until fragrant. Stir in a spoonful of shrimp paste. Pour this mixture over the meat. Season with fish sauce, MSG, and black pepper, mix well, and let marinate for about 1 hour.

Add water to the marinated meat along with the remaining half of the onion and the top half of the lemongrass stalk (cut into 2-inch pieces and smashed). Bring to a boil on the stove. Skim off any foam, then reduce to a simmer and cook for about 1 hour.

Remove the meat, let it cool, and slice thinly. Strain the broth to remove the aromatics for a clear soup. Place cooked rice vermicelli noodles in bowls, top with sliced meat and fresh herbs, then ladle the hot broth over. Add vinegar, lime, or extra chili to taste.