Add the beef bones to a large stockpot and cover with 12 cups of the water. Bring the water to a boil over high heat, reduce the heat to a simmer, and cook for 10 minutes. Using a ladle or large spoon, skim the foam that rises to the top and discard. Remove the bones, rinse them in cool water, and add them to the crock of a 6-quart slow cooker. Discard the broth.

Combine the cinnamon sticks, dried chiles, coriander seeds, fennel seeds, star anise, cardamom pods, and cloves in a small bowl and set aside. Stud the onion halves with the cloves, set aside. 

Season the brisket all over with the kosher salt. In a 12-inch skillet, heat 1 tablespoon of the oil over medium- high heat. Add the brisket, fat side down first, and brown for 3 to 4 minutes per side. Transfer the brisket to the slow cooker, fat side up. Add the ginger, halved onions, garlic, and carrot to the pan and brown for 1 minute (adding the remaining 1 tablespoon oil if necessary).

Add the seasoning mix to the pan and toast for 1 minute. Transfer the contents of the skillet to the slow cooker and add the fish sauce, sugar, 1 1⁄2 teaspoons salt, and the remaining 10 cups water. Cook on high, undisturbed, for 6 hours.

Cook the rice stick noodles according to the package directions and set aside. Arrange the lime wedges, cilantro, mint, basil, bean sprouts, romaine, jalapeños, and sliced onion on a serving platter.

Remove the meat from the slow cooker and set aside on a cutting board. Strain the broth through a fine- mesh sieve into a small pot and cover to keep warm. Discard the vegetables and spices. Chop the meat from the soup bones and knuckle bones and set aside. Slice the brisket.

Remove the meat from the slow cooker and set aside on a cutting board. Strain the broth through a fine-mesh sieve into a small pot and cover to keep warm. Discard the vegetables and spices. Chop the meat from the soup bones and knuckle bones and set aside. Slice the brisket.

To serve, divide the noodles and meat among bowls. Ladle the hot broth over all and serve immediately. Each person should garnish the soup to taste with the ingredients on the serving platter and the condiments.