Prep the steak. Thin the steak across the grain. Allow to dry on paper towels (aids in browning), season a little with salt and pepper.
Cook the noodles. Boil until the package directions tell you to. Lay aside and drain, stirring with a drizzle of sesame oil to keep it in the pan.
Sear the steak. Heat 1 Tablespoon of butter in a skillet on medium-high. Place the slices of steak in a single layer and cook them 2-3 minutes until brown yet tender. Remove from the pan and set aside.
Make the sauce. Lower the heat to medium. Add butter, garlic, and chili flakes. Sauté until fragrant, 30 seconds. Add soy sauce, oyster sauce, and pepper.
Bring it together. Add noodles to the skillet and cover it with garlicky butter. Return the steak, and combine everything until glossy and fragrant.
Finish and serve. Garnish with scallions, cilantro, or parsley. Hot, preferably out of the pan.