Mix above, pour over steak in a shallow dish – after two hours turn steak (total time to marinade 4 hours). Bring out 1/2 hour before grilling. Let sit.
Cook steak, turning once with tongs (not to pierce meat). 6 minutes on each side for medium rare or 8 for medium.
Transfer to a cutting board, let sit 10 minutes. Slice diagonally across the grain.
To avoid wheat, select a wheat-free soy/tamari sauce. If avoiding corn, avoid soy sauce made with corn sweeteners or added caramel coloring.