Preheat a grill to medium high. Combine 2 tablespoons oyster sauce, 1 tablespoon vegetable oil, the five-spice powder, 1/2 teaspoon salt and a few grinds of pepper in a large bowl. Add the chicken and toss to coat.
Oil the grill grates. Grill the chicken until lightly charred and cooked through, 5 to 6 minutes per side. Transfer to a cutting board and let rest.
Meanwhile, bring a medium saucepan of salted water to a boil. Add the noodles and cook as the label directs, adding the carrots and snow peas during the last minute of cooking. Drain the noodles and vegetables and transfer to a large bowl. Wipe out the saucepan and reserve. Snip the noodles into shorter pieces with kitchen shears.
Finely chop the scallions and ginger in a food processor. Heat the remaining 5 tablespoons vegetable oil in the reserved saucepan over medium-high heat. Add the scallion-ginger mixture and cook, stirring, until softened, about 2 minutes. Remove from the heat and stir in the soy sauce and vinegar. Add to the noodle mixture, season with salt and pepper and toss. Divide among plates; drizzle with the remaining 3 tablespoons oyster sauce.