In a medium bowl, combine the chicken pieces with 2 tbsp soy sauce, 1 tbsp cornstarch, 1 tsp sesame oil, and black pepper. Toss until the chicken is evenly coated. Let it marinate for at least 10 minutes while you prepare the other ingredients.
In a separate bowl, whisk together all the sauce ingredients: 1/3 cup soy sauce, honey, hoisin, rice vinegar, sriracha, water, and 1 tbsp cornstarch. Set aside. Mince the garlic and grate the ginger. Cook the noodles according to package directions until al dente, then drain and rinse briefly with cold water to stop cooking. Toss with a tiny bit of oil to prevent sticking.
Heat 1 tablespoon of oil in a large skillet or wok over medium-high heat. Add the marinated chicken in a single layer, working in batches if needed to avoid crowding. Fry for 4-5 minutes per side, until golden brown and cooked through. Remove the chicken to a plate.
In the same skillet, add the remaining 1 tablespoon of oil. Add the white parts of the green onions, the minced garlic, and grated ginger. Stir-fry for just 30-60 seconds until fragrant, being careful not to burn the garlic.
Give the prepared sauce a quick re-whisk, then pour it into the skillet with the aromatics. Cook, stirring constantly, for 2-3 minutes until the sauce thickens, becomes glossy, and bubbles.
Return the cooked chicken and any accumulated juices to the skillet. Add the cooked noodles. Using tongs, toss everything together vigorously for 2-3 minutes until the chicken and noodles are completely coated in the sticky garlic sauce and heated through.
Divide the sticky garlic chicken noodles among dark bowls. Garnish generously with the green parts of the green onions and toasted sesame seeds. Serve immediately.