Vol-au-Vent

Vol-au-vent is a puffed pastry case filled with chicken and button mushrooms bound in a light cream sauce, sharpened with a squeeze of lemon and thickened at the end with a swirl of egg yolk. It's a Friday-lunch fixture of Belgian brasseries from Antwerp to Liège — a dish home cooks make too, but one most guests still order out, since getting the pastry properly crisp and the sauce properly silky takes a kitchen that does it every week.

What it really is

The pastry case — tall, straight-sided, lightly domed — is bought or made separately and baked until it shatters at the fork; it exists only to hold the filling and contributes almost nothing to the flavour itself. The filling is the actual cooking: chicken poached gently in stock, mushrooms sautéed until their liquid is gone, folded into a velouté enriched with cream and finished off the heat with beaten egg yolk and a little lemon juice, which keeps the sauce from tasting flat. A well-made version is pale, glossy and only loosely bound — thick enough to sit inside the case without running, never as stiff as a pot pie filling.

How it's served

• The hot filling ladled into the pastry case at the very last moment, so the base stays crisp under the sauce.
• With a mound of fries on the same plate, almost never rice.
• Sometimes with tiny meatballs or veal quenelles added to the filling for a richer version.

How to write it on the menu

• Name the filling as chicken and mushroom; vol-au-vent on its own is a pastry shape, not a dish, and guests will assume the classic version unless told otherwise.
• Say the pastry is filled to order — a case filled ahead of time turns soft, and regulars notice.
• Flag the cream, butter and egg yolk together; this is a dish built from all three dairy-and-egg allergens at once, not one hidden behind the others.