Poaching fish—gently cooking it in a liquid over low heat—is a classic French technique. Traditionally, the poaching liquid is a light broth, known as a court bouillon, and the finished fish comes out delicious, light, and flaky. That classic technique is the foundation for a different way of cooking fish—poaching in olive oil. Put simply, this method involves submerging a piece of fish (or shrimp) in a bath of warm olive oil and then cooking it in the oven at a low temperature to perfect doneness. The fish emerges with an incredibly tender, silky texture and a pure seafood flavor that’s hard to achieve with any other cooking method. Surely, there’s no better way to pay tribute to a perfectly fresh piece of seafood.
Step one: Season
Remove the fish from the refrigerator, season it, and let it sit at room temperature for about an hour.
Step two: Heat
Heat the oil over low heat just until it reaches 120°F. Use a candy or instant-read thermometer to monitor the temperature.
Step three: Poach
Immediately transfer the pan with the fish to the oven and poach for exactly 25 minutes.
Three Keys to Olive Oil Poaching
The Fish: The best fish for olive oil poaching are rich in flavor and firm in texture—salmon, halibut, tuna, and shrimp all fit the bill. Make sure your fish steaks or fillets are at least 3/4 inch thick (1 inch is even better).
The Oil: Be sure to use extra-virgin olive oil for poaching, because its rich flavor will penetrate the fish. But use a modest brand—not your precious drizzling oil—as you’ll need quite a lot of it.
The Pan: Choose a straight-sided sauté pan or saucepan that will hold the fish in a single layer. It’s fine to crowd the pan as long as the pieces don’t overlap.
One of the remarkable things about this technique is that the timing is virtually foolproof. Twenty-five minutes is the magic number for perfectly cooked seafood. This timing depends on letting the fish sit at room temperature for about an hour before poaching; straight-from-the-fridge fish would dramatically lower the temperature of the oil and throw off the cooking time.
The best doneness indicator is the appearance of white droplets of albumin (protein) on the outside of the fish. You can also use a paring knife to make a small cut in a piece of the fish to visually check for doneness.
Try it Out
Tip: What to do with the leftover oil
Depending on the recipe, you’ll be using 4 to 6 cups of oil to poach the fish. The good news is that you can use the oil a couple more times to poach more seafood. Let it cool to room temperature and then strain it through a fine sieve lined with a coffee filter. Stop straining before you reach the bottom, as any liquid released from the seafood will have settled there. Discard this last bit. Store covered in the refrigerator for up to three weeks.