Soak 8 12-inch wooden skewers in water for 30 minutes.
Thred a piece of steak onto a skewer. Add one mushroom and a piece of onion. Repeat until skewer is full.
Repeat with remaining skewers.
Whisk together the olive oil, garlic powder, salt and pepper. Brush each kabob with the basting oil.
Place the kabobs on the grill and cook for 3-4 minutes. Turn each kabob over and continue cooking for an additional 3-4 minutes or until desired degree of doneness.
Transfer the kabobs to a serving platter and allow to rest for 5 minutes.
Serve immediately with the blue cheese dressing.
Notes
Kabobs can be assembled up to 8 hours in advance and stored in the refrigerator in an airtight container. Bring to room temperature before grilling for best results.