Cut cold boiled codfish in pieces; then boil 8 small onions until soft; heat 2 tablespoonfuls of butter. Add the boiled onions, 2 small cold sliced potatoes, the codfish and 1 cup of milk; sprinkle with pepper. Cover and simmer ten minutes and serve hot.
A leftovers dish: it assumes you already have cooked cod and boiled potatoes in the larder from an earlier meal. Nothing here needs correcting, but a few points of the original's shorthand are worth spelling out.
- Which codThe recipe specifies cold boiled cod, most likely fresh fish poached and left over rather than salt cod — though "codfish" in books of this period can also mean the salted kind. If you start from scratch, poach about 1 lb of skinless fillet in barely simmering salted water for 6-8 minutes, then chill it. Salt cod would need soaking for a day or more and would risk making the dish very salty at this quantity of milk.
- The onions are the dishÀ la lyonnaise simply means "with onions." Eight small onions means whole boiling onions or shallot-sized bulbs, roughly 8-10 oz total; boil them 15-20 minutes until a knife slides through. The original puts everything into the butter at once, but letting the onions take a little colour first is an optional improvement.
- Handle the fish last and lightlyCooked cod is already at its limit. Break it into large flakes, fold it in at the end, and let the pan barely tremble for the ten minutes rather than bubble — a real simmer will shred the fish into threads and curdle the milk.
- Milk, not cream sauceOne cup of whole milk will not thicken on its own; expect a loose, brothy result served in shallow bowls. If you want it to coat, mash one of the potato slices into the butter before adding the liquid, or use half milk and half cream.
- SaltThe original calls only for pepper, on the assumption the fish and potatoes were salted when first boiled. Taste before serving and correct.
- VesselA wide sauté pan or shallow saucepan with a lid, not a deep pot: the potatoes and fish should sit in more or less one layer so they heat through without being stirred.
- YieldTwo generous or three modest servings, as a lunch or supper dish. Good with bread rather than more potatoes.
In French kitchen shorthand, tannounces onions, after the cooking of Lyon, where the onion and butter of the surrounding country are the standard foundation for a dish — the same tag that gives us lyonnaise potatoes. A calendar cookbook like this one leaned on such formulas because they were reliable and, more to the point, thrifty. Recipes for reheating yesterday's boiled fish with onions, potatoes and milk appear under various names in period cookery books, from creamed codfish to cod hash; giving it a French label lifted a plain remainder-of-the-larder supper into something a hostess could put a name to.