Bring 5 quarts water to boil in a large pot. Add salt and noodles, then stir. Cook the noodles al dente according to package directions. (Usually 8-10 minutes.)
Stir-Fry
While you're waiting for the noodle water to boil, heat a large skillet over medium-high heat. Add oil and swirl the pan to coat.
Add the mushrooms and cook until they begin to release their water. (About 4 minutes.)
Add the cabbage, celery, carrots, onions, and garlic. Cook until the vegetables begin to soften (about 3 minutes) but don't let the garlic burn.
In a small bowl, whisk the cornstarch, chicken broth and soy sauce together.
Strain the noodles and add them to the skillet.
Stir the imitation seafood into the skillet.
Pour the sauce over the seafood noodles and vegetables and toss everything together well. Reduce the heat to medium-low and simmer until the sauce is thickened (about 3 minutes).