How to Make It
Heat grill to medium-high. Form the beef into four ¾-inch-thick patties. Use your fingers to make a shallow well in the top of each patty. (This will prevent overplumping during cooking.) Season with a total of ½ teaspoon each salt and pepper.
Oil the grill and cook the patties with the wells facing up for 4 to 5 minutes. Flip and cook until an instant-read thermometer inserted in the center registers 155° F for medium, 4 to 5 minutes more.
Meanwhile, grill the English muffins until toasted, 1 to 2 minutes.
In a bowl, toss the celery, olives, and onion with the oil and lemon juice. Dividing evenly, spread the English muffins with the blue cheese dressing. Form sandwiches with the English muffins, burgers, and celery mixture.