It's a food that's been made to look like something else.
Fish prepared to look like a roast. A castle of cake, with battered battlements and glazed-honey gates. A meatloaf hedgehog. You get the idea.
When I was in film school - a long time ago, in a galaxy far, far, FAR away - they ran a class in special effects where the term ended with a soteltie feast. As I recall, one fellow came in with ice-cream cones that were actually made of mashed potatoes and french fried potatoes...the cognitive dissonance was pretty intense.
Back in the medieval day, before wedding singers and stand-up comedians, sotelties were one of THE big entertainments at feasts. Because of the Church's fast day restrictions on eating, it became the custom to make permitted foods, like fish, look and taste like forbidden foods - like meat. That evolved into food sculpture. And then, as "entremets," to mean any entertainment between the courses of a meal.
In fact, you could make an argument that the return of drama to Western culture began when someone dressed up cod to look like beef stew...
Oh, here are some soteltie recipes. If they turn out well, let us know. If they turn out badly...we're completely not responsible.