Whisk together the gochujang, green onions, soy sauce, rice vinegar, garlic, ginger, sesame oil, and sugar in a small bowl.

Divide the sauce in half and add one half of the sauce into a Ziploc bag.

Put the steak into the bag and put it into the refrigerator to chill (from 30 minutes or up to overnight.)

Cover the remaining of the sauce and chill.

Drizzle the oil into a large pan and heat to a medium-heat temperature.

Transfer the steak from the Ziploc bag to the heated pan. (Set aside the rest of the sauce in the Ziploc bag.)

Cook the steak for 5-8 minutes or until the steak has browned.

Remove the steak from the pan and place it on a cutting board. Set the steak aside.

Add the onions, mushrooms, ramen noodles, ramen seasoning, and the sauce from the Ziploc bag to the pan.

Add the water to the pan and bring it to until it to a simmer. Cook this in the pan for 5-7 minutes.

Make sure that the noodles are cooked through.

With the steak still on the cutting board begin to slice the steak into 1/2 inch slices.

Add the steak and the rest of the sauce to the pan. Continue to cook until the steak is hot.

Garnish with green onions and sesame seeds (optional).