Bring a pot of water to a boil and cook ramen noodles for about 2 minutes, just until they begin to soften. Drain and set aside.
In a small bowl, whisk together soy sauce, hoisin sauce, oyster sauce (if using), brown sugar, sesame oil, and the cornstarch slurry. Set aside.
Heat 1 tablespoon of oil in a large skillet or wok over high heat. Add sliced beef in a single layer and sear until browned and just cooked through. Season with salt and pepper. Remove and set aside.
In the same pan, add another tablespoon of oil and toss in the broccoli. Stir fry for 3–4 minutes until bright green and just tender. Add garlic and sauté for 30 seconds.
Return the beef to the pan along with the cooked ramen noodles. Pour the sauce over everything and toss well to combine. Cook for another 2–3 minutes until everything is hot and the sauce thickens and coats the noodles.
Remove from heat and garnish with sesame seeds, chopped green onions, or red pepper flakes. Serve hot.