Mix all of the ‘secret sauce’ ingredients in a medium bowl. Refrigerate until ready to use.
Cheeseburgers
In a large bowl, add the ground beef, egg white, grated onion, Worcestershire sauce, seasoning salt and pepper. Using your hands or a fork, gently mix together. Shape mixture into 4 thin patties.
Place patties on an outdoor grill or skillet and cook until no longer pink on the inside. About 3 to 5 minutes per side. Place one piece of American cheese over the burgers during the last minute of grilling.
Toast the hamburger buns. Spread the secret sauce on each inner bun. Place grilled patties on bottom bun and top with lettuce, tomato and onion. Enjoy!