You may not recognise it, but it’s an old word for a familiar meal: bacon and eggs or ham and eggs. The first recorded example is so old its English needs translation:
I haue no salt Bacon, Ne no Cokeneyes, bi Crist Colopus to maken.
Piers Plowman, by William Langland, c1350. A cokeneye or cokeney is literally a cock’s egg, a dismissive term for a small or misshapen egg; in another old sense, of a pampered child, it’s the source of Cockney. In modern English, Langland’s sentence would read “I have no salt bacon or small eggs, by Christ, to make collops.”
Later, collop came to refer to the bacon by itself, without the egg; later still to mean any flat, boneless piece of meat, whether raw, fried or roasted. At one time, the Monday before Ash Wednesday was called Collop Monday, because slices of bacon were the usual dinner dish.
It may remind you of escalope, which has led at least a couple of cookery writers to assert that collop is in fact from that French word. Not so. Collop is an old Norse word of which a close modern relative is the Swedish kalops, a meat stew. It may be that the first part of the word is from coal; that origin is supported by this example of its use:
The Scottish Celt is more shifty. In the old days when he had flesh and little else to eat, he could broil it on the coals; and a Scotch collop is perhaps equal to a Turkish kebob. We wonder if in Australia the long-forgotten Scotch collop has been revived? It requires no cooking-vessels. It may be held to the fire on a twig, or laid on the coals and turned by a similar twig — bent into a collop-tongs — or even by the fingers.
Chambers Edinburgh Journal, 14 Feb. 1852. Shifty here doesn’t mean that the Scottish Celt is deceitful or evasive but that he’s able to shift for himself, manage without help, from shift in the sense of an expedient.