Step 1

Whisk 1 tablespoon hoisin, 1 tablespoon soy sauce, and cornstarch together in bowl. Add pork and toss to coat; set aside. Whisk broth, remaining 3 tablespoons hoisin, and remaining 2 tablespoons soy sauce together in second bowl; set aside.

Step 2

Heat 1 tablespoon oil in 12-inch nonstick skillet over medium-high heat until shimmering. Add mushrooms and cook until browned, about 5 minutes. Add ginger and garlic and cook until fragrant, about 30 seconds.

Step 3

Add broth mixture and bring to boil. Arrange noodles in skillet in single layer; cover and reduce heat to medium. Cook until noodles have softened on bottoms (tops will still be dry), about 3 minutes.

Step 4

Uncover skillet and, using tongs, flip noodles and stir to separate. Spread noodles in even layer and scatter broccoli over top. Cover and cook until noodles and broccoli are tender, about 3 minutes, tossing halfway through cooking. Divide noodle mixture evenly among individual bowls; tent with aluminum foil.

Step 5

Wipe skillet clean with paper towels. Heat remaining 1 tablespoon oil in now-empty skillet over high heat until just smoking. Add pork in single layer, breaking up any clumps, and cook without stirring until browned on bottom, about 1 minute. Stir and continue to cook until pork is no longer pink, about 1 minute longer. Divide pork among bowls. Sprinkle with scallions and serve.