Preheat a clean barbecue grill on high. Toast both halves of the bun, face down, in a skillet over medium heat. Set aside. Cut each of the 2 onion rings into quarters. Mix the catsup and relish together. This is you "secret sauce." Form the ground beef into a thin parry slightly larger than the bun. Grill the meat for 2 or 3 minutes per side. Salt slightly. Build the burger in the following stacking order from the bottom up: bottom bun, half of the mayonnaise, pickles, lettuce, tomato slices, onion, beef patty, remainder of mayonnaise, special sauce (catsup and relsih), top bun.