In a bowl, whisk together broth, soy sauce, hoisin sauce, sesame oil, water, rice vinegar, brown sugar, garlic powder, ginger, corn starch and red pepper flakes until well combined.
Toss with steak slices and broccoli until everything is evenly coated. If freezing, place in zipper freezer bag freeze. Thaw when ready to cook.
When ready to cook, preheat the oven to 400 degrees.
Line a sheet pan with a large piece of parchment (I like mine to come up over all sides) or foil.
Spread beef and broccoli into a single layer on the pan and pour all remaining marinade over the beef and broccoli.
Bake for 20-25 minutes until broccoli is fork tender, beef is cooked and sauce has slightly thickened. Serve immediately over rice and spoon sauce over as well.