Pôchouse

Soften the aromatic base. Melt 20 g of the butter in a wide 4-litre casserole and soften the onion with half the salt for 5 minutes. Add 15 g garlic and thyme for the final minute. The onion is translucent and fragrant without browning. A pale aromatic base keeps the wine sauce clean rather than roasted. Keep butter from scorching and wipe any raw-fish drips from the work area separately.

Reduce the wine broth. Pour in the 750 ml wine and 300 ml fish stock and simmer uncovered for 12 minutes. The liquid has reduced modestly and smells less sharply alcoholic while remaining plentiful enough to poach the fish. A brief reduction concentrates the wine before delicate fish enters the pan. Wine may retain alcohol after cooking; avoid leaning over vigorous steam.

Start the firm fish first. Add the firmer zander and carp pieces in one layer and poach at a bare simmer for 3 minutes. The outer surfaces have turned opaque while the centres remain underdone. Firm fish starts first so all species can finish together. Use a clean fish slice and avoid splashing hot wine broth.

Add the tender fish and check temperature. Add the perch and trout, continue the bare simmer for 5 minutes and check the thickest pieces from each species for 63 °C. Lift all fish carefully to a warm platter. Every species reaches 63 °C and the pieces remain whole enough to lift without flaking apart in the liquid. Staged addition prevents tender fish from overcooking while firm fish catches up. Check for pin bones as the fish is transferred and remove any found before service.

Bind the sauce away from the fish. Mash 40 g softened butter with 40 g flour to a smooth paste. Whisk small pieces of the paste into the simmering wine broth and cook for 2 minutes, then season with the remaining salt, pepper and parsley. The sauce lightly coats the back of a spoon without becoming gluey. A butter-flour liaison thickens the broth after the fish is removed, protecting the fish from rough whisking. Keep the sauce at a controlled simmer to prevent splashing.

Toast the garlic croutons. Spread the baguette slices with the remaining 20 g butter and toast for 8 minutes in a 200 °C oven, then rub lightly with the remaining 5 g garlic. The croutons are dry at the edges and golden, with garlic aroma but no burnt surface. Dry croutons absorb sauce at the table without dissolving immediately. Use oven gloves and handle the cut garlic carefully on hot bread.

Coat and serve immediately. Return the fish to the sauce only long enough to coat, then divide fish and sauce among four warm bowls and add two garlic croutons to each. The fish is coated in sauce and remains in distinct pieces, with two crisp croutons per serving. Minimal final handling protects the fragile cooked fish. Give each portion a final visual check for small bones and state that freshwater fish can still contain them.