Prepare the sauce: In a bowl, combine light soy sauce, dark soy sauce, black vinegar, sesame oil, and sugar together.
Cook noodles according to package instructions. Drain noodles and reserve 1-2 tbsp of hot noodle water. Add noodle water to the sauce and mix until creamy.
Mix noodles and sauce together. Garnish with green onion and add chili oil. Serve hot and enjoy!
