Wash and dry the potatoes.
Use a fork to prick a few holes in the potato.
Microwave the potatoes for 5-10 minutes
Allow the potatoes to cool slightly.
Using a sharp knife cut the potato (the short way) about 1/4-1/2", making sure to not cut all the way through to the bottom.
Place the potato on a piece of aluminum foil big enough to wrap the entire potato.
Stuff the slices carefully with slices of onion.
Drizzle several tablespoons of dressing over the potato.
Fold the aluminum foil around the potato tightly.
Repeat with the remaining potatoes.
Place the potatoes on the grill and allow them to finish baking for 15-20 minutes.
Unwrap the potatoes and serve warm with a drizzle of olive oil