• Bring a small pot of water to the boil and blanch the oxtails for 5 minutes. Bring a second, larger pot with 8 cups of water to a boil.
  
• Rinse and transfer the oxtails to the second pot along with the lemongrass and shallots. Simmer on low for 3.5 hours. Add the brisket and continue to simmer for another 2 hours for 5.5 hours total. Use a slotted spoon to remove the lemongrass and shallots. Take the oxtail and brisket out and store in a container. Transfer the soup to another container and put everything in the fridge.
  
• While the soup is simmering, mince the lemongrass for the satế and transfer it to a food processor along with the shallot, garlic, and Thai chilies. Pulse into a fine paste.
  
• Heat the oil in a medium saucepan over medium-high heat until it shimmers. Add the satế paste and fry, stirring, just until fragrant, 1 to 2 minutes. Remove from the heat and stir in the chili flakes, sugar, fish sauce, and shrimp paste (if using). Let cool then place in a jar or airtight container. The satế will keep in the fridge for up to several weeks.
  

To Assemble

• Bring a large pot of water to a boil and cook the noodles according to the package directions, usually 10-15 minutes for properly thick vermicelli. Meanwhile, heat up your bowls by filling with hot tap water. In a second saucepan, combine the soup with enough water to make 8 cups then bring to a low simmer. Slice the brisket and place into the soup to reheat, along with the halved meatballs, and sliced ham. When the noodles are done, drain in a colander, and rinse well with cold water and allow 2-3 minutes to dry.
  
• Drain your bowls, then divide the noodles evenly between the bowls and top the noodles with the brisket, beef balls, and ham. Scoop on 1-2 tablespoons of the satế depending on your taste for saltiness and spiciness - you can always add more later.
  
• Ladle on the piping hot broth. Enjoy immediately topped with banana blossoms, sliced onions, sawtooth coriander, cilantro, Thai basil, and lime.