Green’s Dictionary of Slang

(Aus.) a lump, a chunk; thus yunk of dodger, a slice of bread (cf. dodger n.² ).

1921		Mirror (Perth) 7 Aug. 4/2: A real sincere Bohemian in the street, is always well worth risking being bowled over by one of Henry Phord’s‘yunks of tin’ whilst crossing Hay-street for jaw wagging purposes.
1940		Lachlander Recorder (NSW) 25 Jan. 6/3: Sausages are ‘snorkers.’ A slice of bread is called a ‘yunk of dodger.’.
1941		Baker Popular Dict. Aus. Sl. 24: Dodger, food of any kind. Also, a ‘yunk of dodger’, a slice of bread.