Cut the beef into ½-inch cubes. Lightly season with the salt and black pepper.

Heat the oil in a cast iron or a non-stick frying pan over medium high heat. Tilt the pan, moving it back and forth and side to side until bottom of the pan is coated with the oil. Add the beef and cook for a few minutes until light brown, about 4 minutes. Carefully drain accumulated juices, if there is any. Stir in the butter and cook until the butter has melted and the beef is nicely browned. Drain and set aside.

Bring 4 cups of water to a boil. Add both kinds of noodles and both packets of vegetable mix. Cook, stirring occasionally, until the noodles are al dente, about 4 minutes. Remove from heat.

Strain the noodles over a glass bowl. Return the strained noodles back into the pot with a cup of the noodle water. Turn the heat to medium. Add the entire packet of the Chapagetti soup base mix and half of the seasoning mix from the Neoguri packet. Stir until well combined and sauce has slightly thickens. Remove from heat. Stir in the oil from Chapagetti packet.

Transfer the noodles to a serving plate. Top with the browned beef and sprinkle with the chopped green onion. Serve with kimchi.