1) Pat the steak dry with paper towels and season both sides generously with salt and freshly ground pepper.
2) Heat a cast iron pan on high until nearly smoking. Add a tiny slick of oil and place your steak in the middle of the pan and cook, without moving for 2-4 minutes. Flip and cook for another 2-3 minutes. (Or cook to desired doneness.) Remove from the pan and let rest while you cook the noodles.
3) Heat up a touch of oil over medium high heat. Brown the mushrooms and onions, letting the mushrooms sear before stirring. When browned, add the water and stir in the soy sauce and bouillon cube, making sure to dissolve.
4) Add the water and bring it to a boil. Then add the noodles and cook until tender and most of the liquid evaporates, about 6-8 minutes, or according to the package. Remove from the heat.
5) Slice the steak against the grain. Divide evenly among two dishes, top with the sliced steak, salt and pepper to taste, and red pepper flakes if desired. Enjoy!