In a large bowl, combine beef and steak seasoning, mixing lightly but thoroughly. Shape into twenty 1/2-in.-thick patties. Grill burgers, covered, over medium heat 3-4 minutes on each side or until a thermometer reads 160degrees., In a large bowl, combine lettuce, burgers, cheese, croutons, tomato, onion and pickles. Serve with salad dressing.Freeze option: Place patties on a plastic wrap-lined baking sheet; wrap and freeze until firm. Remove from pan and transfer to a resealable plastic freezer bag; return to freezer. To use, cook frozen patties as directed, increasing time as necessary for a thermometer to read 160degrees.