A court bouillon is a quick-cooked poaching liquid built from water, an acidic ingredient such as wine or vinegar, and aromatic vegetables and herbs. The French name means "short broth," distinguishing it from a proper stock: a stock simmers for hours to pull body from bones, while a court bouillon simmers briefly and is used the same day rather than reduced or clarified.
A basic version simmers onion, carrot, celery, bay leaf, and peppercorns in water with white wine or vinegar, sometimes with thyme or parsley added toward the end. It's used to poach delicate fish fillets, shrimp, lobster, and hard-boiled eggs, as well as vegetables like artichokes and asparagus, without adding a heavy flavor of its own. Less commonly, it poaches chicken or veal, where the acid helps tenderize the meat.
Regional versions vary the aromatics - fennel, saffron, or citrus zest are common additions when the liquid is meant to complement a specific fish or shellfish. Once used, the strained liquid can be kept and reused as a light base for a sauce or soup.