Preheat grill to a medium-high heat, about 400-425°F.
Grease the grill grates with olive oil.
Wash potatoes and cut into wedges. Add to a large bowl and toss with the olive oil, salt, pepper and garlic powder.
Once hot, place the potato wedges onto the grill grates and grill for about 6 minutes until deep grill marks form on one side. Flip and grill for another 6 minutes on the other side. Test the tenderness with a skewer. If the potatoes need more cooking time, turn off burners on one side of the grill and move potatoes to that area. Continue cooking over indirect heat for a few more minutes until tender.
Remove the potato wedges from the grill. Serve with lemon wedges and chopped green onions or chives.