Cotriade is Brittany’s founding fish stew — the Breton fisherman’s one-pot meal that historically used the unsaleable portion of each day’s catch, simmered with potatoes in a cauldron (kaoter in Breton) on the boat or the quayside. Unlike bouillabaisse with its saffron-tomato-garlic identity, cotriade is deliberately austere: the sea provides the flavor, and the cook’s only job is not to interfere. The base begins with thinly sliced onions and a bouquet garni (thyme, bay, parsley) softened in salted butter (always salted in Brittany) in the bottom of a deep pot. Potatoes, peeled and sliced 1cm thick, are layered over the onions. Water or a light fish stock is added to just cover, brought to a simmer, and cooked for 15 minutes until the potatoes are nearly done. The fish is then added in sequence based on density: firm-fleshed species (conger eel, monkfish, gurnard) first, followed 5 minutes later by medium fish (pollack, whiting, mackerel), and delicate fish (sardines, small sole) for just the final 3-4 minutes. The poaching temperature must remain at 78-82°C — the fish should set gently, not boil apart. The cotriade is served in two acts: the broth first, ladled over thick slices of stale bread rubbed with garlic in deep bowls; then the fish and potatoes on a separate platter. A sauce of the broth’s stock sharpened with cider vinegar and chopped sorrel (or a vinaigrette) accompanies the fish. The dish demands whatever is freshest that day — prescribing specific species misses the point. Authenticity lies in the method, not the ingredients list.
Whatever fish is freshest that day (minimum 3-4 species). Onions and potatoes form the base, simmered in water or light stock. Fish added in sequence by flesh density. Poach at 78-82°C, never boil. Served in two acts: broth over bread, then fish and potatoes. Vinegar-sorrel sauce alongside.
The conger eel is the secret weapon of cotriade — its gelatinous flesh enriches the broth enormously. Ask your fishmonger for the cheapest, freshest assortment and build around it. The bread for the broth course should be dense, day-old pain de campagne. The vinaigrette-sorrel sauce is essential: it cuts the richness and provides the acid balance the dish otherwise lacks. In Séné, Morbihan, the cotriade is made with cider instead of water — an excellent variation.
Using a single fish species (defeats the purpose). Boiling the fish (falls apart, broth becomes cloudy). Adding fish before potatoes are nearly cooked. Using olive oil instead of butter (wrong region). Making a complex fumet base (should be simple — the fish ARE the flavor).
La Cuisine Bretonne — Simone Morand; Les Recettes de la Mer en Bretagne