First, preheat oven to 375ºF and spray a 9-inch x 13-inch casserole dish with nonstick cooking spray.
Then, sprinkle the white rice onto the bottom of the casserole dish.
Next, prepare veggies. Cut broccoli into bite-sized pieces and finely dice a large red pepper and half a yellow onion. Add those to the casserole dish.
Prepare sauce by mixing together soy sauce, hoisin, minced garlic, maple syrup, red chili sauce, beef broth, and water. Set aside.
Prepare flank steak by placing it in between 2 pieces of parchment paper. Then, using a meat tenderizer, tenderize meat until it's around 1/2-inch thick. This will help break down the beef and make it a lot less chewy.
Next, slice the beef into 1/2-inch pieces and add it to the casserole dish.
Pour the sauce over steak, veggies, and rice, and use a large wooden spoon to mix everything together.
Cover casserole dish with a piece of tin foil and bake at 375ºF for 20 minutes.
Remove from oven and mix. Cover again and bake for an additional 15 minutes.
Remove from oven and uncover. Then, bake for an additional 10-15 minutes, uncovered or until the beef is fully cooked and the rice is no longer crunchy.
Let sit for around 5-10 minutes before serving to let the sauce fully soak up.