1. To prepare relish: Combine pickle relish, mustard, ketchup and sriracha sauce in a small bowl and stir to blend; reserve.
2. Shape ground beef into four 5-inch round patties; season to taste with salt and black pepper. Heat a heavy cast iron pan or griddle over medium heat. Add patties and cook on each side for 5 minutes, or until cooked to desired doneness. Top each burger with a slice of cheese and heat briefly to melt cheese.
3. To assemble burgers: spread 1 tablespoon mayonnaise on bottom half of each bun; top each evenly with shredded lettuce, red onion, white Cheddar burgers, crispy bacon slices and spicy mustard relish. Close with top halves of buns.
Optional: To “autograph” your plate, use a mustard squeeze bottle and shake it well, so it is thoroughly mixed. Making sure the top cap is turned where it will not interfere with the flow of the mustard, hold it about two inches away from the plate. In one continuous loop, using cursive, write the name of a child or an encouraging word!