Preheat the oven to 300 degrees.
Begin by making the Lemongrass Beef: Dry off the beef and sprinkle with the salt, pepper, and garlic powder. Heat the oil in a Dutch oven on medium heat. Sear the beef on all sides. Then, add the rest of the ingredients, cover the pot, and bake for three hours.
After the beef has cooked for two and a half hours make the soup: In a Dutch oven on medium heat the oil, and add the garlic, ginger, and lemongrass and cook a minute. Add the chicken stock, carrots, soy sauce, fish sauce and sugar and bring to a simmer. Simmer for 10 minutes, or until the carrots are tender.
Also, bring an inch of water to a boil in a three- quart saucepan. Add the asparagus and simmer covered for four minutes. Drain.
Also, cook the rice noodles according to the package directions. Drain.
Remove the beef from the oven. Remove the lemongrass and shred the beef with two forks.
To serve the soup, place some shredded beef, vegetables, and noodles in each bowl, and then pour the soup on top. Garnish each bowl with lime wedges, sliced peppers, scallions, and cilantro.