Specifically designed for poaching whole fish, a fish kettle is an oblong-lidded pan typically made from copper, aluminum or stainless steel. The average kettle is just over 20 inches long, requiring the use of two stovetop burners for even heating. You can poach salmon in stock, salted water or milk. Court bouillon is a traditional poaching broth that takes its flavor from dry white wine, a handful of roughly chopped vegetables and herbs and spices. While poaching a whole salmon in a fish kettle isn’t a labor-intensive process, it does require a bit more time than grilling or roasting.
Combine the cold water, dry white wine, white wine vinegar, carrots, onions, celery, leeks, cloves of garlic, bay leaves, parsley and thyme sprigs, white peppercorns and salt in a large stockpot set over medium-high heat. Bring the ingredients slowly to a boil. Cover the pot and let the broth simmer for 30 minutes.
Pour the liquid through a fine-meshed strainer into a large saucepan. Set the saucepan over medium-high heat. Return the broth to a boil, then reduce it to a fast simmer. Simmer the broth uncovered for 15 to 20 minutes or until it’s reduced by half.
Remove the pan from the stovetop. Let the 7 1/2 cups of broth that remain go cold.
Rinse the fish thoroughly under cold running water to wash away any stray scales. Pat it dry, inside and out, with paper towels.
Place the salmon in a fish kettle set over two burners. Pour all of the cold broth over the fish. If necessary, add more cold water to ensure the entire fish is covered in liquid.
Bring the broth slowly to a boil with the lid on the kettle. As soon as the liquid is simmering, remove the kettle from the stovetop and place it on a heatproof surface.
Leave the fish in the lidded kettle until the broth goes completely cold.
Lift the cold salmon out of the broth and set it on a large cutting board. Pat it dry with paper towels.
Make a cut around the salmon’s head and down its backbone with a sharp knife. Peel back the skin back starting at the head end. At the tail end, cut the skin away and discard it. Carefully turn the fish over and skin the other side.
Transfer the salmon to a large serving platter. Garnish the platter with sprigs of parsley and lemon wedges and serve with aioli sauce, if desired.