In a medium sized bowl whisk together the marinade ingredients. Pour over the steak cubes in a large food storage bag or shallow casserole dish. Seal or cover and marinate in fridge at least 1/2 hour and up to 2 hours
Make the skewers. Alternate between the steak pieces and cooked potato.
Heat a grill or grill pan to medium-high and lightly oil. Add the kebabs and grill about 5-6 minutes on both sides, flipping every 3 minutes, until the steak reaches the desired temperature.