Start by preparing the ingredients: Rinse and slice the mushrooms as well as the spinach. Cube the onion into small pieces, and mince the garlic cloves. Preheat a wok to medium-low heat, and then add the cooking oil. Add garlic, onion, and mushrooms to the wok and sauté for three to four minutes, and stir occasionally.
Make the Noodle Sauce: Add the following ingredients to a small bowl to blend the sauce: black bean paste, sesame seed oil, soy sauce, sugar, paprika powder, and rice vinegar. Add salt to your taste.
Cook the Noodles: Start cooking the noodles at this point, as they only take three minutes to cook thoroughly. Remove the noodles once cooked.
Add the sauce: Pour the sauce, then add the spinach and noodles. Lower the temperature to the minimum setting. Add the black bean paste sauce to the wok and stir everything to coat the aromatics and mushrooms. Add the spinach and noodles to the wok.
Toss to coat and serve immediately: Use a tong to coat the noodles with the delicious sauce. This step should take no longer than one minute to preserve the vibrant colour of the spinach and also prevent the noodles from overcooking. When done, garnish with sesame seeds to serve.