Cook noodles according to package instructions. Drain and set aside.
In a small bowl, mix soy sauce, brown sugar, hoisin sauce, and cornstarch. Set aside.
Heat oil in a large pan over medium-high heat. Add sliced steak and cook until browned, about 3-4 minutes.
Add garlic, ginger, and red pepper flakes, and sauté for 1 minute.
Pour in the sauce mixture and beef broth. Stir well and let it simmer until slightly thickened.
Add cooked noodles to the pan and toss everything together until well coated.
Garnish with green onions and sesame seeds. Serve immediately!