Hamburger of the country." Louis Lassen of Louis' Lunch, a small lunch wagon in New Haven, Connecticut, is said to have sold the first hamburger and steak sandwich in the U.S. in 1900. "New York" magazine states that "The dish actually had no name until some rowdy sailors from Hamburg named the meat on a bun after themselves years later", noting also that this claim is subject to dispute. A customer ordered a quick hot meal and Louis was out of steaks. Taking ground beef trimmings, Louis made a patty and grilled it, putting it between two slices of toast. Some
What Love Is Made Of extremely positive about "What Love Is Made Of", describing it as "darker than anything" from "On a Mission", while calling it "slinky". The reviewer went on to commend the "irresistibly pouty" chorus. Pitchfork Media's Katherine St. Asaph commented that, in the song, the singer "sound[ed] completely enthralled, by either her lover or the music" and complimented her voice, noting that it seemed "ten times bigger than before". Jordan Sargent of "Spin" magazine called the track "exuberant" and highlighted Katy's vocal performance, which he deemed "typically fantastic", while the team from pop music website Popjustice gave "What Love Is Made Of"