An oldie but a goodie. Inspired by Pop's Perfect Burger Recipe.
Slice a yellow onion paper thin. Allow a palm-size amount per burger. Roll ground beef into large meatball size spheres. Press the meatball between two salad plates (or approximate size), so that the burgers are thin.
Heat a non-stick pan over medium high and spray with non-stick spray or olive oil. When the pan is hot, place a pile of the thin onion slices topped with the now seasoned (salt and pepper) burger. Press down a bit with a spatula. Grill for about 2 minutes, then flip, including the onions and grill the other side for just 1 minute longer (or to your liking).
If you are feeling very carnivorous, or manly, make it a double with cheese...