Instructions

Whisk 1 teaspoon five-spice powder, 1 teaspoon soy sauce, and ½ teaspoon sesame oil together in medium bowl, then stir in 1 trimmed and thinly sliced pork tenderloin to coat; let sit at room temperature for 15 minutes. Meanwhile, bring 2 quarts water to boil in large saucepan. Add 6 ounces fresh Chinese noodles and cook, stirring often, until tender. Reserve ⅓ cup cooking water, drain noodles, and rinse thoroughly with cold water; set aside.
Whisk remaining 1 tablespoon soy sauce, remaining 1½ teaspoons sesame oil, 1½ tablespoons hoisin, 1 teaspoon chili-garlic sauce, and reserved cooking water together in bowl. Heat 1 teaspoon vegetable oil in 12-inch nonstick skillet over medium-high heat until shimmering. Add cooked noodles; half of hoisin mixture; 6 scallions, white parts thinly sliced and green parts cut into 1-inch pieces; 1½ teaspoons grated ginger, and 1 minced garlic clove and cook until fragrant, about 30 seconds; season with salt and pepper to taste. Transfer to individual serving bowls, cover with aluminum foil to keep warm, and set aside until ready to serve.
Heat 1½ teaspoons vegetable oil in now-empty skillet over high heat until just smoking. Add half of pork and cook until browned on both sides, about 2 minutes; transfer to clean bowl. Repeat with 1½ teaspoons vegetable oil and remaining pork; transfer to clean bowl and cover with foil to keep warm.
Heat remaining 2 teaspoons oil in again-empty skillet over medium-high heat until just smoking. Add 4 halved heads baby bok choy, cut side down, and 1 tablespoon water, cover, and cook until bok choy begins to brown, about 2 minutes. Flip bok choy and continue to cook, covered, until second side is browned and bok choy is tender throughout, 1 to 2 minutes. Top noodles with pork and bok choy and drizzle with remaining sauce. Sprinkle with 2 teaspoons toasted sesame seeds and serve with extra chili garlic sauce.