Bring the pot of water to a boil and let the noodles soak in the boiling water according to the package instructions. Meanwhile, rub the meat with olive oil, sprinkle with cumin and a pinch of salt, and rub a bit all over. Place in a very hot pan and sear on all sides. Add the onion, ginger, and pepper and cook for a few minutes, then add the mushrooms, broth, and pak-choi. Drain the noodles and add them to the pan. Mix and adjust the seasoning. Slice the meat and serve the noodles and bok choy in a large bowl, with the slices of meat on top. Pour the broth from the pan over the top.