In a small bowl, whisk together soy sauce, garlic, brown sugar, ginger and pepper; set aside.
In a large pot of boiling water, add Yaki-Soba until loosened, about 1-2 minutes; drain well.
Heat olive oil in a large skillet or wok over medium-high heat. Add onion and celery, and saute, stirring often, until soft and transparent, about 3-4 minutes. Stir in cabbage and cooked chicken and saute until heated through, about 3 minutes.
Stir in Yaki-Soba and soy sauce mixture and toss until well combined and the noodles are heated through, about 2 minutes.
Serve immediately.
Recipe by Wishes and Dishes at https://wishesndishes.com/panda-express-chicken-chow-mein/