Cut the beef tenderloin into bite-size pieces.
Slice the onion, bell pepper, broccoli, and other vegetables into bite-size pieces.
Season the beef with salt and pepper.
Heat olive oil in a pan over high heat and sear the beef on both sides.
Remove the beef and stir-fry the vegetables.
Combine the beef and vegetables, add steak sauce, and stir-fry to finish.
Plate the dish nicely.