Combine an egg yolk, the seasoning packet, sauce packet, kewpie mayo, freshly minced garlic, and sesame oil and mix it all together in a bowl.
Boil the noodles for 3-4 minutes. Take a couple tablespoons of the hot noodle water and add it to the base mix, then whisk it all together.
Add the cooked noodles and the rest of the pasta water to the bowl and mix, then top with cooked steak, an egg, sesame seeds, lime juice, or whatever toppings you like.
