Preheat oven to 425˚F. Spray a large sheet pan with non-stick cooking spray. Set aside.
In a large bowl, add soy sauce, beef broth, brown sugar, garlic, ginger, salt, and pepper; whisk until sugar is fully dissolved. Add the steak, and marinate for 30 minutes or up to 1 hour.
Transfer the steak to the sheet pan (without the marinade). Dip the broccoli into the marinade (just for a few seconds) and quickly place on the sheet pan with the steak.
Roast for about 10 to 12 minutes, or until the steak is cooked through and the broccoli is fork-tender.
Meanwhile, heat the remaining marinade in a small saucepan and bring to a boil over medium heat.
In a small bowl, combine cornstarch and water and stir to make a slurry. Add cornstarch mixture to the saucepan and whisk for 1 minute or until sauce has just started to thicken. If desired, add about 1/4 to 1/2 cup water for a thinner sauce.
Once the beef and broccoli are done, evenly drizzle with the sauce until completely coated. Finish off with a drizzle of sesame oil and top with green onions and sesame seeds. Enjoy!