Pierce potatoes several times with a fork and place on a microwave-safe plate. Microwave on HIGH (100% power) for 3 to 4 minutes until potatoes are still firm but soft enough that a skewer can be inserted. Place potatoes on a plate and cool 5 minutes. Slice in half.
Alternate steak cubes, potatoes, onion, and tomatoes on skewers. Brush skewers with olive oil and sprinkle with Member's Mark™ Pink Himalayan and Black Peppercorn Grinders, coating all sides. Grill over Medium Direct heat for 8 to 10 minutes, turning once, until potatoes and onions are lightly browned and steak reaches desired doneness.