~Saute celery in butter in a small saucepan until tender. Stir in oregano, salt, garlic powder, and pepper. Remove butter mixture from heat, and keep warm.

~Wash potatoes; cut each into 1/2-inch slices, cutting to, but not through, bottom peel.

~Place a slice of onion between each slice of potato.

~Place each potato on a square of heavy-duty aluminum foil; drizzle about 2 tablespoons butter mixture over each. Fold foil edges over, and wrap securely.

~Grill foil-wrapped potatoes over medium coals 1 hour or until done.