In a large stockpot, add beef shank, oxtail pieces, and pork hock. Cover with water and bring to a boil. Boil for 5 minutes, then drain and rinse the meat thoroughly to remove impurities. This creates a clearer, cleaner broth.

Return cleaned meat to the pot with 4 quarts of fresh water. Add sliced onions, smashed ginger, lemongrass stalks (bruised), and 2 tablespoons salt. Bring to a boil, then reduce heat to low and simmer uncovered for 2.5-3 hours until meat is tender.

While broth simmers, prepare annatto oil by heating vegetable oil in a small pan and adding paprika. Stir for 30 seconds until oil turns deep red. Remove from heat and set aside.

After 2 hours of simmering, remove meat from broth. Let cool slightly, then slice beef shank and separate pork hock meat from bones. Return bones to broth and continue simmering.

Season broth with fish sauce, adjusting to taste (approximately 4-6 tablespoons). Add the prepared annatto oil and stir well. The broth should be deeply flavored, slightly salty, and vibrant reddish-orange.

Cook noodles according to package instructions. Drain and divide among serving bowls.

Arrange sliced beef and pork over noodles. Ladle hot broth over the top, ensuring each bowl gets plenty of liquid.

Serve immediately with fresh herb platter including cilantro, lime wedges, thinly sliced cabbage, sliced onions, and chile peppers on the side for customization.