Start by boiling water in a large pot. Once boiling, add the rice noodles and cook according to package instructions (usually around 5-7 minutes). Drain and set aside.
In a bowl, mix the soy sauce, oyster sauce, hoisin sauce, and brown sugar until combined. Set the sauce aside.
Heat the vegetable oil in a skillet or wok over medium-high heat. Add the minced garlic and ginger, sautéing for about 1 minute until fragrant.
Add the sliced flank steak to the skillet. Stir-fry for approximately 5 minutes until the beef is browned and cooked through.
Add the broccoli florets and sliced bell pepper to the skillet, cooking for another 3-4 minutes until the vegetables are tender yet crisp.
Pour the sauce over the beef and vegetables, stirring to coat everything evenly. Allow it to simmer for about 2 minutes to let the flavors meld.
Add the cooked noodles to the skillet, tossing everything together until the noodles are well-coated with the sauce.
Serve the sticky beef noodles hot, garnished with chopped green onions and sesame seeds, if desired.