Heat olive oil in a large skillet over medium-high heat.
Add the sliced steak and cook until browned, about 3–4 minutes. Remove and set aside.
In the same skillet, add broccoli and cook for 4–5 minutes until tender-crisp. Add minced garlic and stir for 1 minute.
Return the beef to the pan. In a bowl, whisk together soy sauce, brown sugar, sesame oil, and beef broth.
In a separate small bowl, mix cornstarch with water. Stir into the sauce mixture and pour over the beef and broccoli.
Cook for 2–3 minutes until the sauce thickens. Serve over cooked rice, garnished with sesame seeds and green onions if desired.