Remove season packet from Original flavor Udon noodles. Pour half of the season packet into a small bowl and combine with a pinch of salt and pepper. Season both sides of the steak with the mixture.
Heat a medium cast iron pan over medium high heat until very hot. Add ½ teaspoon sesame oil making sure the pan is well coated. Peel and slice ginger thinly. Slice 1 serrano pepper and add both to the hot pan. Toss in broccollini and cook, stirring for 3 minutes or until broccolini is just tender.
Remove cooked broccolini to a plate and keep until ready to plate
Bring pan back up to heat and add another ½ teaspoon sesame oil. Sear the first side of the NY steak for 3 minutes. Flip the steak and add the spring onions.
Cook steak for another 3 minutes.
Using a tong, also sear both fatty sides of the steak.
Remove the onions from the pan and set aside
Add 1 teaspoon of soy sauce to the pan. NOTE: The soy sauce will splatter so be careful at this step. Cook the steak for 30 seconds and flip it over and turn off the heat. Spoon onions and pan juices over the steak. Allow the steak to rest while making the soup.
De-glaze the steak pan with 1 cup beef broth, Add water and bring to a boil.
Add the remainder of the udon seasoning packet and udon noodles to the hot broth. Stir to combine and cook noodles for 3-5 minutes.
Divide the cooked noodles into bowls and then ladle broth over. Serve with sliced steak, hard boiled eggs, cooked broccolini and chopped spring onions.