Cutlets of Kingfish, Mayonnaise Mousseline

A Delmonico's trick of the trade: a fish mousseline shaped like a chop, crumbed and fried, with a cold sauce alongside. Everything depends on the forcemeat being cold and the poaching liquid never boiling.

• The hinge: poach below a simmerHold the water or fish stock at 165-175F so the surface barely shivers. A boil will blow the quenelle apart or make it spongy; the cutlets are done when set through and firm to the touch, roughly 8-12 minutes depending on thickness.
• What kingfish means hereIn an 1890s New York kitchen this is the northern kingfish, or whiting, a small Atlantic drum landed along the eastern seaboard. It is not king mackerel. Any lean firm white fish works: whiting, hake, cod, pollock, or halibut trim.
• Fish quenelle forcemeat, in modern termsRanhofer's No. 90 is a fish quenelle forcemeat of the usual type: raw fish pounded with a panada and butter, bound with egg and seasoning, then let down with cream. A food processor does the work in a minute: 1 lb fish, 2 egg whites, 1 tsp salt, pulsed cold, then 1 to 1 1/4 cups heavy cream added slowly. Keep the bowl, blade and cream refrigerator-cold or the mixture will break.
• Molding without cutlet moldsMetal cutlet molds are long gone from most kitchens. Pipe or spoon the forcemeat into small oval pools on buttered parchment, or press it into a lightly oiled ramekin and turn it out; a short piece of pasta or a trimmed skewer pushed in after poaching stands in for the chop bone.
• Chill before breadingThe text says poach until consistent enough to egg and crumb. Take that seriously: cool the cutlets completely, ideally an hour in the refrigerator, before flouring, egging and crumbing, or the coating will slide off in the pan.
• Clarified butterButterfat alone, with the milk solids removed, will take the 340-350F needed to brown crumbs without burning. Ghee is the same thing off the shelf; a half-and-half mix of butter and neutral oil is a workable substitute.
• Mayonnaise mousselineNo. 615 is mayonnaise lightened with stiffly whipped cream, folded in just before service. It deflates within the hour, so make it last. If raw yolks are a concern for the table you are feeding, use pasteurized eggs or a good bottled mayonnaise as the base.
• Napkins and paper frillsDressing on napkins means a folded linen napkin on the platter to absorb frying butter; the frills are the paper cuffs still sold for crown roasts and lamb chops. Both are pure presentation and can be skipped.
• YieldA pound of fish makes eight to ten small cutlets, enough for four as an entrée in the modern sense or eight as a course in the nineteenth-century sense.