No. 471

Gooseberry Sauce

Sauce aux Groseilles Vertes a Maquereau

Cut off the stalks and remove the black spots from half a pound of gooseberries; blanch them in an untinned copper vessel for two minutes, drain and add them to a pint of Hollandaise sauce (No. 477) or instead of using them whole they may be rubbed through a sieve and the pulp mixed with the Hollandaise sauce.

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For the Modern Kitchen Do not make this as written.

A two-ingredient sauce whose whole character depends on the gooseberries staying sharp and the Hollandaise staying warm, not hot. The one instruction to ignore is the copper vessel.

Skip the untinned copperBare copper was used to hold the green colour of acidic fruit, and the reaction that greens the fruit is copper dissolving into it. Gooseberries are acidic enough to pick up a meaningful amount; blanch them in stainless steel and accept a duller colour.
QuantitiesHalf a pound is about 225 g of gooseberries, roughly a cup and a half whole. A pint of Hollandaise in Ranhofer's kitchen is 16 fl oz, about 2 cups, which is a large batch.
Which gooseberriesThese are hard, green, underripe fruit picked in early summer, not the sweet dessert varieties. If only ripe ones are available the sauce turns cloying and needs a squeeze of lemon to hold its edge.
Two minutes means two minutesThe blanch is only meant to soften the skins and knock back the raw astringency. Beyond that the berries collapse and leak water, which will thin and eventually break the Hollandaise.
Drain thoroughlyAny blanching water carried into the sauce is the main cause of separation here. Drain the fruit well and let it cool to warm before folding it in, since boiling-hot fruit will scramble the yolks.
Whole or sievedThe sieved version gives a pale green, evenly tart sauce; the whole-berry version gives bursts of acidity against the butter. Sieve while the fruit is still warm, and press hard, as gooseberry skins are tough.
Holding itHollandaise sits safely only in a narrow warm band. Keep it near 140F in a bain-marie and use it within the hour rather than reheating.
Yield and serviceA pint of sauce is enough for roughly eight portions of fish. Its intended partner, as the title says, is mackerel.

A Little History

The name points to the sauce's use: groseille à maquereau is the ordinary French word for gooseberry, and vertes marks these as green, unripe fruit; the mackerel in the name is usually explained by the traditional pairing, though that is tradition rather than settled etymology. Serving a plain gooseberry sauce with oily fish is long established in English cookery, well before Charles Ranhofer set this version down in The Epicurean (1894), the compendium of his years at Delmonico's in New York. Here the berries are folded into a full pint of Hollandaise, so the acid cuts the butter and the butter rounds the acid. Blanching in untinned copper was a recognised nineteenth-century trick for keeping green fruit and vegetables bright; the toxicity of copper taken up this way was argued about at the time, and the practice was abandoned.