Beef Manhattan is a dish consisting of roast beef and gravy. It is often served with mashed potatoes either on top or on the side. A variation on this dish is Turkey Manhattan, which substitutes turkey for the roast beef. The term "Manhattan" is a misnomer as the beef and turkey variants are usually referred to as "open-face sandwiches" in New York and much of the eastern United States and the term "Manhattan" is limited to the Midwest, the South, and parts of the western United States. It is unlikely that restaurants in the New York City area would understand what a customer was asking for if the diner used the "Manhattan" phrase.
The dish was first served under the name "Beef Manhattan" in a now defunct Indianapolis deli in the late 1940s where it gained traction as a Hoosier staple. In Indiana, it is served on bread. The roast beef is sliced and put on bread like a sandwich, then cut corner to corner and plated in a V shape. Mashed potatoes are served between the two halves, and the whole is covered in gravy.