You can use either sweet noodle sauce or soybean sauce for fried noodles. Generally speaking, sweet noodle sauce is sweet with a slightly spicy taste and a reddish color, which makes it more suitable for highlighting the sweet and tangy taste of the fried sauce. Soybean paste, on the other hand, is a sauce made from fermented soybeans, which has a stronger flavor and is suitable for adding aroma and freshness to the fried sauce. The exact choice of sauce can be determined by your own taste and ingredients. If you like a sweeter fried noodles, you can choose sweet noodle sauce. If you like fresh flavor and aroma, you can choose soybean sauce.