Yakisoba is a Japanese dish made with fried wheat flour noodles flavored with bits of meat and vegetables.
The noodles that work best in the dish is Chuka soba (a simple wheat flour noodle) or you can use fresh ramen noodles. The traditional buckwheat soba noodles are typically used for this dish but they can be.
The traditional meat would be pork belly but you can substitute bacon or even chicken or beef.
The sauce recipe may vary but one version includes tonkatsu or oyster sauce, Worcestershire sauce, soy sauce and mirin. There are bottled versions available. One of the best found in the U.S. is imported from Japan. You can but it on Amazon: Yakisoba Sauce- Otafuku.
Here is simple Yaki Soba sauce recipe enough for about 1lb of noodles:
1 tablespoon chicken bouillon cubes
1 tablespoon oyster sauce
5 tablespoons tonkatsu sauce
Combine the ingredients in a small bowl and stir occasionally until the bouillon cubes dissolve. You can also use bouillon granules which will dissolve faster. Make sure not to add the sauce to you dish too early or the noodles will get soggy.