In a bowl, combine the thinly sliced beef sirloin with Szechuan peppercorns, soy sauce, cornstarch, and sesame oil. Mix well to ensure all the beef is coated. Cover and let it marinate for at least 30 minutes.

Broth

Prepare the Broth

In a large pot, add the beef broth, ginger, minced garlic, chili paste, chopped green onions, soy sauce, fish sauce, and water. Bring the mixture to a boil over medium-high heat, then reduce the heat and let it simmer for 20 minutes to allow the flavors to meld.

Cooking the Noodles and Assembling the Soup

Cook the Noodles

While the broth is simmering, cook the egg noodles according to the package instructions. Drain and set aside.

Cook the Beef

In a separate pan, heat a little oil over high heat. Add the marinated beef and stir-fry quickly until it is cooked through, about 3-5 minutes.

Assemble the Soup

In serving bowls, place a portion of cooked egg noodles, followed by the stir-fried beef, bok choy, and bean sprouts. Pour the hot broth over the top. Garnish with fresh cilantro and serve with lime wedges on the side.