Place all marinade ingredients in a medium bowl and whisk to combine.
Slice steak against the grain into thin strips. Place the marinade in a zip lock bag along with the steak strips and peppers. Remove the air from the bag, zip it closed and refrigerate at least 1 hour and up to 24 hours.
Drain the marinade from the steak and peppers and discard.
Pan fry the steak and peppers until no longer pink and peppers are soft.