What is the name of the steamed burger style associated with New Haven, Connecticut?

The steamed cheeseburger is the burger style associated with New Haven, Connecticut.

Instead of being grilled or fried on a flat cooking surface, a steamed cheeseburger is cooked in a small metal mold inside a steam cabinet. The steam cooks the beef gently and gives the patty a soft, moist texture. Cheese is often steamed at the same time, then placed on the cooked patty.

The style is especially associated with Louis' Lunch in New Haven, a restaurant that claims to have served an early hamburger sandwich since 1900. Another long-running Connecticut restaurant, Ted's Restaurant in Meriden, is also strongly identified with steamed cheeseburgers. These establishments helped preserve a regional method that differs from the dominant griddled style.

A steamed cheeseburger should not be confused with a slider, which usually refers to a small sandwich, or a butter burger, whose defining feature is butter used during cooking or assembly. The key distinguishing feature here is the use of steam rather than a griddle or grill.