In a bowl, combine peanut butter or sesame paste along with sesame seeds, chili oil, Chinese black vinegar, light soy sauce, sugar, grated garlic, and msg. Mix until combined and the sauce is smooth.
Cook noodles according to package directions or desired doneness. Mix in 1/4 cup of the cooking water to the sauce mixture to create your sauce, then add the drained noodles and mix.
Top with crushed peanuts, scallions, and chili oil and enjoy!