Soak the beef shank in cold water for about 2 hours to remove excess blood and impurities for a clearer broth. Rinse and drain well.
In a large pot, add the whole beef shank, the toasted spices, beef stock, onion, and tomato.
Bring to a boil, then lower the heat and simmer for 40 minutes to 1 hour, until you can poke through with a chopstick with slight resistance. Remove the beef and cut into chunks.
In a wok or large pan, heat oil over medium heat. Add onion, ginger, and garlic, and stir-fry until browned and fragrant. Stir in Doubanjiang and cook until the oil turns red and aromatic.
Add the beef chunks and rice wine, stir-fry for a minute to let the alcohol evaporate slightly. Then add the simmered broth, soy sauce, and dark soy sauce.
Bring everything to a boil, then reduce to low and let it simmer for another 30 minutes, until the beef becomes fork-tender and the broth turns rich and flavorful.
Taste and adjust salt as needed.
Boil the wheat noodles and vegetables, then place them in a bowl. Ladle the soup and beef over the noodles and top with a spoonful of pickled mustard greens. Add chili oil if you like extra heat.