Cook potato noodles according to package instructions. Rinse under cold water and drain well.
Heat 2 tablespoons of oil in a wok over medium heat. Add garlic and ginger, stir-fry until fragrant.
Add doubanjiang and cook for about 30 seconds.
Add soy sauce, dark soy sauce, vinegar, sugar, and water. Stir to combine.
Add cooked noodles and toss until evenly coated with the sauce.
Drizzle in sesame oil and top with green onions. Stir well.
Serve hot and garnish with sesame seeds if desired.