In a heatproof bowl, combine gochugaru, gochujang, green onion, garlic, and sesame seeds. Heat the 3 tablespoons of oil in a pot until it reaches 350°F. Add to the bowl (it will sizzle) and stir to combine.
In the same bowl, add peanut butter, mirin, soy sauce, rice vinegar and sesame oil. Mix well to combine and set aside.
Cook dried noodles according to packaging instructions. Drain, reserving ¼ cup of water, then add noodles directly to the sauce bowl.
Mix well and use reserved cooking liquid to thin the sauce as needed.
Garnish with additional sesame seeds or green onion and serve immediately.
Notes
These noodles should be made as close to serving as possible for the sauce to remain creamy.