Prep the bones. Rinse the beef marrow bones under cool water and scrape away any remaining tissue. Soak in water for 1–2 hours to remove blood and impurities.

Cook the bone stock. Place the bones in a pressure cooker with 2 onions, 6 stalks lemongrass, 50g ginger, the halved garlic bulb, and 2.2 liters water. Select the "Soup" function on "Low" and cook for 30 minutes to get a clear, aromatic broth.

Make the spice sachet. Put 50g chopped lemongrass, 6 pressed garlic cloves, and 1 tbsp peppercorns into a tea filter or muslin bag.

Build the beef broth. In a separate pot, add the spice sachet, 2 onions, 50g ginger, 300g pineapple, 3 stalks lemongrass, and 2 liters water. Season with 1 tsp salt, 1 tbsp rock sugar, and 2 tbsp fish sauce. Bring to a boil, skim off the scum, then add the beef shank. Cover and simmer for 60–75 minutes, checking tenderness after 60 minutes — pierce with a fork or chopsticks to test.

Prepare the Huế shrimp paste. Mix 100g shrimp paste with 100ml boiling water. Cover and let it sit for 2 hours.

Make the chili sate. Heat 80ml cooking oil over medium-low heat. Fry the minced lemongrass until fragrant, then add minced shallot, then minced garlic, frying each until fragrant. Add the minced chili and mix well. Season with 1 tsp chicken powder and 1 tsp fish sauce. Stir in the annatto oil for color.

Combine the stocks. Once the beef shank is tender, combine the bone stock with the beef broth.

Season the broth. Add the shrimp paste mixture (adjust to taste), skimming off the scum as it rises. Season with 1 tsp salt, 1 tsp rock sugar, and 3 tsp chicken powder. Simmer on low heat for 20–30 minutes, skimming regularly to keep the broth clear.

Prep the herbs and vegetables. Clean and slice the spring onion, purple onion, and Vietnamese mint.

Slice the beef shank into bite-sized pieces, and slice the chả lụa.

Assemble the bowl. Add 2 tbsp chili sate to the pot (or add directly to individual bowls). Drop the mọc into the simmering broth and cook for 3–5 minutes, until they float and are cooked through. In each bowl, add rice noodles, sliced beef shank, chả lụa, and mọc. Ladle over the hot broth and top with the fresh herbs, bean sprouts, shredded water spinach, and shredded banana flower.