Cut the chuck flap steak into bite-sized pieces.
Chop the onion, bell pepper, and broccoli into pieces easy to eat.
Season the chuck flap steak with salt and pepper.
Heat olive oil in a pan and sear the steak pieces on high heat until browned on both sides.
Push the beef to one side, add the vegetables, and stir-fry.
Stir-fry beef and vegetables together, add oyster sauce, ketchup, and steak sauce, and mix well.
Once everything is cooked through, turn off the heat. Finished!