You may be asking yourself, “How do I poach fish? How do I even ‘poach’ anything?” It’s a technique that sounds fancy and complicated, but is actually quite simple. Poaching is a gentle cooking method that uses water (or other liquid) heated to a low temperature, typically between 158°F and 176°F, or 70°C to 80°C. This delicate approach is perfect for a light and healthy meal. The fish is gently cooked in a flavorful broth made from lemon and white wine, ensuring that it stays moist and tender. Such a preparation would be perfect served with a side of steamed vegetables or a light salad. This description comes from the 1962 guide for new wives, A Bride’s Cookbook.
To poach is to simmer in liquid. It is the most delicate way to cook fish, but if you do it, you must be prepared to make a sauce. For your purposes, the kinds of fish best suited to poaching are filets of sole, flounder or halibut, and salmon or turbot steaks. The poaching is the same for each, but certain sauces are best with certain fish. The sauces will follow. Tiny peas, asparagus and new potatoes all go well with poached fish.
Butter a shallow baking dish. Season 2 filets or 2 steaks with salt and freshly ground black pepper. Put them in the dish and sprinkle with the juice of ½ lemon. Add ½ cup dry white wine or dry vermouth. Water may be substituted, but wine is much better. Cover tightly with aluminum foil and bring to a boil over moderate heat. This will take only a minute or two. Lift an edge of the foil and peek. As soon as the liquid is boiling, lower the heat as far as it will go and simmer for 8 minutes. Remove the fish to a warm platter and cover it with foil. Strain the juices remaining in the dish into a bowl if you are cooking sole, flounder, or halibut. You will need them for various sauce recipes, like White Wine Sauce.