Combine all the ingredients and stir until corn starch dissolves.
Bring a medium pot of water to boil.
Slice flank steak in to ⅛th slices across the grain.
Transfer in to a medium bowl with a few tablespoons of rice vinegar and a pinch of salt.
Mix meat with vinegar and set aside.
Cut the broccoli heads in to large bite size pieces and blanch in boiling water for 60 seconds.
Remove, drain well, and set aside.
Coat the bottom of a large skillet with vegetable oil and stir fry garlic and ginger for 60 seconds.
Add sliced peppers and stir fry until they become tender.
Remove peppers and set aside.
Add broccoli to pan and cook just until a knife can easily pierce the stalk.
Set broccoli aside.
Transfer steak to a paper towel and dry thoroughly.
Add some more oil to the pan and heat the steak for no more than 30 seconds per side.
Add peppers, broccoli, and green onions to the pan. Stir to combine.
Clear an area in the middle of the pan to add the stir fry sauce. Stir as you slowly add it to the pan.
Stir Fry well until all the ingredients are well coated with the sauce.
Serve garnished with some thinly sliced green onion, cilantro, sesame seeds or crushed peanuts.
