Green’s Dictionary of Slang

Aberdeen cutlet n.

a dried haddock.

1890		London Dly News 1 Feb. 4/7: An ‘Aberdeen cutlet’ is a dried haddock.
1890–1904		Farmer & Henley Sl. and Its Analogues.
1937		Yorks. Eve. Post 12 Feb. 10/6: A dried haddock can be known as an ‘Aberdeen cutlet’.
1949		W. Granville Sea Sl.
1987		I. Doig Dance at the Rascal Fair 21: ‘Mahogany horse at dinner, Aberdeen cutlet at supper.’ Which was to say, dried beef and smoked haddock.