Poaching is a classic French method in which a chef gently cooks something (usually fish) in a liquid over low heat. Traditionally, that liquid is a light broth, known as a court bouillon. If done correctly the finished fish comes out delicious, light and flaky.
The Italians took that method a step forward, substituting extra virgin olive oil as the liquid, and it’s the foundation for an entirely different way of cooking. This is not deep-frying. Submerging a sturdy fillet of fish such as halibut or tuna into a bath of warm olive oil and then cooking it in the oven at a low temperature is to many a revelation. The fish comes out of the bath with a remarkably tender, silky texture — with a pure seafood flavor that’s hard to achieve with any other cooking method. It’s moist, but never watery, and any residual oil is not burnt or acrid, but rather light, sweet and slightly peppery.
Not only does this method lead to alternative taste and texture, it provides chefs with an additional use for olive oil — one of the healthiest oils on the planet given that it’s rich in monounsaturated fatty acids and vital polyphenols.
One of the remarkable things about the poaching technique is that the timing is virtually foolproof. Twenty-five minutes is the magic number for perfectly cooked seafood every time. Chefs will let the fish sit at room temperature for about an hour before poaching because cold fish from the refrigerator will lover the temperature of the oil dramatically. The best doneness indicator is the appearance of white droplets of albumin (protein) on the outside of the fish. Or you can make a small cut in the fish with a paring knife to visually check for doneness.
There are three keys to perfect olive oil poaching. First, make sure that the fish you choose is rich in flavor and firm in texture, and is cut into at least 1-inch thick fillets. Choose a straight-sided sauté pan or saucepan that will hold the fish in a single layer to the pieces don’t overlap. Finally, be sure to use extra-virgin olive oil for poaching, because its rich flavor will penetrate the fish. In the interest of cost, do not use high-end finishing oils, but rather good-quality extra virgin oil.
Normally you will use between 4 and 6 cups of oil to poach the fish. Be sure to save the oil in order to extend it into a few more poaching sessions. Let it cool to room temperature and strain it through a fine sieve lined with a coffee filter. Store covered in the refrigerator for up to three weeks.
Following are the steps to poach fish in olive oil:
- Step 1: Remove the fish from the refrigerator, season it, and let it sit at room temperature for about an hour.
- Step 2: Heat the oil over low heat just until it reaches 120 degrees. Use a candy or instant-read thermometer to monitor the oil’s temperature.
- Step 3: Immediately transfer the pan with the fish to the oven, and poach for exactly 25 minutes. When plating the fish, drizzle with a little of the poaching oil, and spritz with lemon juice.