Minced meat or fish with bread-crumb, egg, etc., rolled into a ball or small cake and fried. Known at least since 1706 (OED). Mollard 1802 uses a mix of fowl meat, ham, cucumber and anchovy in egg-and-crumb.

Original Receipt in 'The Art of Cookery Made Easy and Refined' By John Mollard (Mollard 1802)

RISSOLES.
Cut into small slips breast of fowl, lean ham/ pickle cucumbers, and anchovies; add to them consume [sic], cayenne pepper, breadcrumbs, and raw yolks of egg. Simmer them over a fire for five minutes, and be careful not to let the mixture burn. Then put the mixture on a plate, and when cold, cut into pieces, and dip them in yolk of raw egg, afterwards in fine breadcrumbs, and mould them with the hands into what form you please. Have ready boiling lard, fry them of a nice colour, drain them dry, and serve them up with fried parsley under.



Making Rissoles
National Training College of Domestic Science, Westminster, 1944