Just made my own Jucy Lucy and it was the best burger ive ever had. Do it some time you wont regret it.
My version was two patties with med. chedder inbetween.
Sweet onion buns toasted with garlic butter.
Mushrooms sauteed in butter and red wine vinegar.
Mayo on bun and thats it. No veggies or anything on this it would only take away from the awesomeness of the Jucy Lucy
Pic not mine (I couldnt stop to take a pic, to good!)