Cook the instant ramen according to the package instructions, reserving some of the hot pasta water.
In a bowl, combine the egg yolk, Kewpie mayonnaise, and soy sauce.
Add a bit of the hot pasta water to the mixture to create a creamy sauce.
Once the noodles are cooked, drain them and mix them with the sauce until well combined.
Top the ramen with sliced green onions and drizzle with chili oil to taste.
