Cut lettuce on either side of the core and make 4 large lettuce cheeks. Place on dinner plates cut side up.
In a small bowl, combine sour cream, relish, ketchup, 1 teaspoon Worcestershire sauce, salt and pepper.
Season the meat with remaining teaspoon of Worcestershire, salt and pepper. Form 4 large, thin patties that are thinner at the center than edges for even cooking.
Heat a cast-iron griddle or skillet over medium-high heat. Add patties and cook 6 minutes, turning occasionally. Top each patty with 2 slices of yellow American cheese; tent with foil to melt.
Place patties on the lettuce cheeks and top with pickles and onions. Pour dressing over burgers and lettuce and sprinkle burger salads with sesame seeds.