Young hake ready for cooking with  vegetables and herbs.
habari1/iStock/Getty Images

Specialized pieces of cookware, such as fish poachers, represent a dilemma for dedicated home cooks. As wonderful as it is to always have exactly the right tool for the job, even commercial kitchens don't have room for every possible item. Still, if you love seafood, there are strong arguments for having a fish poacher on hand. Its narrow shape makes it relatively easy to store, and there's no more practical way to poach whole fish or large whole fillets.

The Basic Anatomy

Fish poachers are recognizable at a glance, thanks to their distinctive shape. They're long, narrow ovals, typically 6 to 8 inches in width and 18 to 24 inches in length, with a matching lid. Inside you'll find a flat platform for the fish, with drainage holes and a pair of handles for easy lifting. Modern designs are typically made from durable stainless steel, with copper or aluminum encased in the heavy base for better heat distribution. Vintage models were often made of copper, and can sometimes be found in thrift stores or antique shops. These can be longer than modern versions, making them suitable for bigger fish but occasionally too large for your stove.

Your Poaching Liquid

Before you can poach your fish, you need to choose your poaching liquid. The traditional choice, a simple broth known by the French term "court-bouillon," literally means short -- or quick-cooking -- broth. It's made by simmering peppercorns, herbs and aromatic ingredients such as onions or shallots in a mixture of water, white wine or white wine vinegar. It should be strained and cooled before you begin. Fish stock provides another versatile choice, or you can infuse your fish with specific flavors and colors by cooking it in a thinned sauce. You might even opt for a flavorful olive oil or rich clarified butter as your poaching liquid.

The Poaching Method

Clean and scale your fish, or have the fishmonger do it for you. Season it inside and out, if whole, or on both sides if it's in the form of large fillets. You might also line the cavity of the fish with citrus fruit, fresh herbs, onions or other aromatic ingredients, for added flavor. Lay your fish on the poacher's insert and lower it into the poacher. Cover the fish with room-temperature broth or court-bouillon, and arrange your poacher across two burners. Bring it to a gentle simmer and then poach the fish approximately 10 minutes per inch of thickness. You can also poach in a gentle oven, preheated to a temperature of 250 to 300 degrees Fahrenheit.

The Finishing Touches

Your fish is done when it flakes or when the dorsal fin pulls out evenly. The USDA's recommended final temperature for fish is 145 F, when tested with an internal thermometer, though lean fish might be overcooked and dry at that temperature. Use your poacher's handles to lift the fish from its poaching liquid, and allow it to drain for a minute or two before transferring it to a serving platter. If your fish is to be served cold, chilling it in its poaching liquid prevents drying and allows more flavor to infuse. For an elegant presentation, carefully peel away the skin on one side, and then glaze the exposed area with plain gelatin to keep it shiny and moist.