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Oysters Au Gratin
Plunge twenty-four large, freshly opened oysters in three-quarters pint boiling water with a teaspoon salt and boil for three minutes. Drain on a sieve and keep the liquor. Briskly knead in a small saucepan one tablespoon butter with two tablespoons flour for a minute. Place the pan on the fire, pour in one and a half gills oyster broth and two gills hot milk. Season with half teaspoon salt and two saltspoons cayenne pepper; gently mix. Cut each oyster in four pieces and add to the pan, lightly mix, then let boil for two minutes. Transfer the preparation into a deep baking dish, dredge two tablespoons grated Parmesan cheese over and set in the oven to bake for ten minutes. Remove and serve.
A straightforward cream-and-cheese oyster gratin whose only real trap is the cooking time: the oysters are boiled, simmered again in the sauce, then baked. Cut the early cooking hard and the dish stays tender.
- Gills and saltspoonsA gill is half a cup (4 fl oz), so one and a half gills of oyster broth is 3/4 cup and two gills of milk is 1 cup. A saltspoon is a quarter teaspoon, making two saltspoons of cayenne a full half teaspoon — aggressively hot by current taste; start with an eighth of a teaspoon and adjust.
- The hinge: don't cook the oysters three timesOysters are done the moment their edges ruffle, roughly a minute in simmering liquid. Poaching three minutes, boiling two more in the sauce, then baking ten will produce something closer to erasers. Poach barely a minute for the liquor, fold the cut oysters into the finished sauce off the heat, and let the oven do the rest.
- Oven heatNo temperature is given at all. For a ten-minute bake that browns the cheese, use 425F, or slide the dish under the broiler for two or three minutes once it is bubbling.
- Freshly opened oystersThe recipe assumes you shuck them yourself and catch the liquor. Shucked oysters sold in tubs work: use their packing liquor plus enough water to make the three-quarters pint, and skip the salt teaspoon, as bottled oyster liquor is already salty.
- The rouxKneading butter and flour in a dry pan for a minute before it goes on the fire is an odd instruction; simply melt the tablespoon of butter, stir in the two tablespoons flour, and cook a minute without colouring before adding the warm broth and milk. Add the liquid in stages to keep it smooth.
- Parmesan and browningTwo tablespoons of grated Parmesan over a dish this size gives savour but little colour. A tablespoon of fine dry breadcrumbs mixed into the cheese helps it brown evenly in the short bake.
- YieldTwenty-four oysters in about three-quarters of a pint of sauce serves four as a first course, or two as a main with bread. Bake in one deep dish or in individual gratin dishes, which shortens the bake to about six minutes.
"Au gratin" names a method rather than a sauce: the browned crust formed on top, from the French gratter, to scrape — originally the crusty bits scraped from the dish. Oysters were cheap and everywhere in American cities at the turn of the twentieth century, sold by the barrel and the hundred, which is why cookbooks of this period run through dozens of oyster preparations: fried, stewed, panned, scalloped, in patties, and dressed in French style like this one. The framing here is classic hotel-kitchen practice — a small white sauce enriched with the oyster's own liquor so nothing of the flavour is thrown away, then a dusting of Parmesan and a fast pass through a hot oven.