Sole au Champagne

Sole au Champagne teaches the architecture of a classical fish sauce in one clean line: a shallow poach, an exact reduction, velouté, and a montée au beurre (cold butter whisked in off the heat). The one true thing to know before touching the pan is that the poaching liquor is not a by-product. It is the sauce, so the fish must cook gently and the liquor must reduce by half, no more and no less.

The original assumed a saucier on staff, fish stock never off the fire, and a salamander waiting to glaze the platter. At home, use a prepared small batch of fish velouté, a one-quart saucepan, and the broiler you already own. The brigade's separate stations and service-held sauce are scaffolding, so they go; the poach, reduction, butter finish, glaze, and last-minute julienne stay, because they are the dish. The quantities here feed four, one cook, one stove, one evening.

At the table, the sole should be pearly and tender beneath an ivory-gold sauce, with two little heaps of crisp fish providing the bite the soft preparation needs. Have the cold butter cubed and the julienne cut before the reduction begins. The one step that decides the dish is the montée au beurre: the pan must leave the heat before the butter goes in, and the sauce must never boil again.