A tavern sandwich, also known as a loose hamburger or loose meat sandwich, is a combination of ground beef and onions served on a roll with pickles, mustard and ketchup. It was originally developed for sale at a restaurant in Iowa in the 1920s. One defining feature of the tavern sandwich is the way the meat is ground so it is all in uniform, small grains that adhere to each other when placed inside a roll. Many home recipes attempt to emulate the diner version of the sandwich, with nostalgic cooks actively rejecting the use of low-fat or otherwise unauthentic ingredients. Other recipes attempt to elevate the tavern sandwich through the use of expensive ingredients or more elaborate cooking methods.
The base for a tavern sandwich is ground beef. The original sandwich had the beef ground and cooked in such a way that it could be loaded onto rolls with an ice cream scoop. The actual method of how the meat was ground is not known, but the original cooking method started by browning the ground beef in lard with diced onions. Once the meat and onions were cooked, water was added to the pan until it just covered the beef, after which it was allowed to simmer down until the water was gone. The now very moist meat was then spiced with salt, pepper and vinegar to give it a distinct taste unlike a normal hamburger.
The roll used is a Kaiser roll that has been split down the center. The authentic preparation has the roll steamed until it is warm and very pliable. Updated versions of the tavern sandwich have the roll being baked or even fried in butter to create a crisp surface for the meat to sit on. Each side of the interior of the roll is smeared with yellow mustard, and then ketchup. Slices of dill pickle are put on the roll and, occasionally, a slice of Swiss cheese.
The beef is then gathered in an ice cream scoop and placed inside the steamed roll. The top of the roll is then pressed down, wrapping the meat largely in the center so it can be eaten without too much of a mess. Home cooks and other restaurants often modify the original tavern sandwich recipe by adding other condiments, such as mayonnaise or horseradish. Non-traditional recipes also sometimes use Dijon or stone ground mustard instead of yellow mustard, or substitute flavored salad dressing for the plain vinegar.