Season the steak with salt and pepper.
(optional) Using a jaccard-type meat tenderizer, score the meat numerous times in 2 directions.
Cut steak into approx 1/2" - 1" cubes.
Whisk together all marinade ingredients in a bowl, set 1/2 cup aside.
And add the cubed steak to the remaining portion, coating all sides.
Let marinade for at least 4 hours, preferably overnight.
Cut peppers and mushrooms into 1" - 2" chunks.
Place the vegetables and meat on skewers as desired.
Cook on a hot grill for 8-12 minutes (depending on desired level of doneness), brushing the kabobs with the 1/2 cup of marinade set aside as the kabobs are turned/flipped on the grill.