Make the sauce. Whisk together the soy sauce, oyster sauce, hoisin sauce, sesame oil, brown sugar, cornstarch, and red pepper flakes in a small bowl. Set aside.

Cook the broccoli. Heat 1 tablespoon of oil in a large wok or skillet over high heat. Add the broccoli and stir fry for 3–4 minutes until bright green and just tender-crisp. Remove from the pan and set aside.

Brown the beef. Add the remaining oil to the pan. Add the ground beef and cook, breaking it up as you go, for about 5–6 minutes until fully browned. Drain excess fat if needed.

Add aromatics. Push the beef to one side and add the garlic and ginger to the center of the pan. Cook for about 30 seconds until fragrant, then stir it all together.

Combine everything. Return the broccoli to the pan, pour the sauce over everything, and toss to coat. Cook for another 1–2 minutes until the sauce thickens and everything is well coated.

Serve. Garnish with sliced green onions and sesame seeds. Serve immediately over rice or noodles.