Wash and dry the potatoes.

Use a fork to prick a few holes in the potato.

Microwave the potatoes for 5-10 minutes (depending on your microwave strength) until they are soft, but not too soft. (About 80% baked.)

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.

Heat a grill to 400 degrees.

Place the potatoes on the grill and allow them to finish baking for 15-20 minutes. Because grills can vary in heating, move/adjust the potatoes to a different spot on the grill every 5 minutes so that they cook evenly.

The bottoms of the potato should get slightly crispy because of the oil in the dressing.

Unwrap the potatoes and serve warm.