Thinly slice potatoes (1/4 inch think or less) and onion. Toss potatoes with olive oil, garlic and salt and pepper.
On a large piece of foil (12-16 inches long) lay out half the potatoes. Top with 1/2 the butter. Layer on the remaining potatoes and top with the remaining butter.
Fold up the foil and seal tightly, wrap again in a second piece of foil. Store in a ziploc bag if traveling.
Cook on the grill over medium heat for 25-30 minutes turning every 5-10 minutes. Top with your favourite toppings; green onions, sour cream or cheddar cheese. Enjoy!
