Prepare rice if needed.
Roughly chop bell pepper, broccoli, zucchini, onion. Mince garlic.
Slice skirt steak if not pre-sliced!
Set veggies aside and prepare stir fry sauce.
In a large pan on medium heat, add olive oil and beef. Brown for about 6 minutes or until medium/well done.
Remove beef and add veggies to the pan. Cook covered for about 5 minutes, stirring occasionally.
Once veggies are cooked through, add in stir fry sauce and reduce heat to low.
Mix cornstarch with water until it creates a slurry. Add to the sauce/veggie mixture and stir until sauce thickens.
Add beef back in and simmer until ready to plate.
Add stir fry over rice and top with sesame seeds.