Court-bouillon is not a stock but a quickly made aromatic poaching liquid designed for a single use — to gently cook fish, shellfish, offal, or vegetables while imparting flavour rather than extracting it. The name means 'short broth,' reflecting its 20-minute preparation time. The classical composition varies by purpose: for fish, water is simmered with white wine, white wine vinegar, sliced onion, carrot rounds, a bouquet garni of thyme, bay, and parsley stems, and whole white peppercorns. For shellfish, add fennel fronds and a strip of lemon zest. For sweetbreads and brains, increase the vinegar and add a sliced lemon to help firm and whiten the protein. The liquid is always prepared in advance and cooled to the appropriate temperature before the protein enters — dropping a cold piece of fish into boiling court-bouillon causes exterior proteins to seize violently, producing a dry, flaky surface over a raw centre. For whole fish, start in cold court-bouillon and bring to a bare simmer. For portions, the liquid should be at 70-80°C when the fish enters. The court-bouillon itself is typically discarded after use, though for shellfish preparations, the strained and reduced liquid becomes nage — a light sauce in its own right. A well-made court-bouillon should smell of wine and herbs, taste gently acidic, and add a subtle background flavour to whatever is cooked in it without masking the protein's own character.
Prepare and cool before adding protein — never drop food into boiling court-bouillon. White wine and vinegar provide acid that firms fish protein and brightens flavour. Simmer aromatics 20 minutes to extract flavour before use. Single-use liquid — designed to give flavour, not extract it. Temperature control: 70-80°C for portions, cold start for whole fish.
For the most elegant poached fish, wrap the portion in muslin before lowering into the court-bouillon — this prevents the flesh from catching on the pot and tearing. If the court-bouillon will become a nage, use fish fumet as the base liquid instead of water for a richer result. Add a star anise to the bouquet garni when poaching lobster — it has a natural affinity with crustacean sweetness.
Adding fish to rapidly boiling liquid — exterior seizes, interior stays raw. Under-seasoning — the liquid should taste of something before the fish enters. Using it as a stock substitute — court-bouillon lacks collagen and body. Oversimmering the aromatics — beyond 30 minutes, bitter vegetable compounds leach out.
Escoffier, Le Guide Culinaire; Larousse Gastronomique