Homard Thermidor

Lobster Thermidor took shape in Paris in the early 1890s and is named after Thermidor, the play by Victorien Sardou that premiered at the Comédie-Française on 24 January 1891 — a drama about the fall of Robespierre so politically charged that radical Republicans rioted at its second performance and the government banned it from state theatres, where it did not reopen until 1896. Thermidor is also a summer month of the French Republican Calendar, the source of the play's title. The dish's exact authorship is disputed: it is variously credited to the restaurant Maison Maire near the Porte Saint-Denis theatres, to a Café de Paris kitchen run by chef Léopold Mourier (a former assistant of Auguste Escoffier), and to a Chez Marie dated by some accounts to 1894 — claims that conflict and that no single source establishes. What is firmly recorded is that the preparation entered the codified canon when Escoffier set down a version in Le Guide Culinaire (1903). The original sauce is generally said to have been seasoned with English powdered mustard; Dijon is the usual choice in modern kitchens.

The gratin top is the first thing: a blistered, deep-gold cheese crust that crackles under the fork and gives way to a hot, loose creamy sauce beneath. The lobster itself is sweet and firm with a gentle snap, its brininess folded into the richness of cream and egg yolk. Mustard and cognac run underneath as a sharp, faintly boozy warmth that keeps the dish from turning cloying, and the whole thing arrives bubbling in its own shell, smelling of toasted cheese and shellfish.

The body of the dish is a mornay sauce. A roux — equal parts butter and flour cooked together — thickens milk into a béchamel as the flour's starch granules swell and gelatinise; off the heat, grated Gruyère is stirred in to melt into a mornay, and an egg-yolk-and-cream liaison enriches it and helps it set. Mustard does double duty: its compounds emulsify the fat for a smoother sauce and its pungency, with the cognac and white wine, cuts through the cream. The decisive step is the gratin. Spooned over the lobster and slid under a hot broiler, the cheese-and-sauce surface loses water and browns fast: the milk and cheese proteins and sugars undergo the Maillard reaction while exposed sugars caramelise, building the golden, nutty, slightly bitter crust. High overhead heat colours the top before the delicate lobster beneath can overcook and turn rubbery — the reason a broiler, not a slow oven, is used.