A quick dip in vinegar before cooking can bring a layer of flavor you never expected.
Fish cooked with flashes of acidity, specifically with a little vinegar, is ingrained in our cooking subconscious. Cones piled with battered fish and chips love a few shakes of malt vinegar. A whole roasted branzino has never suffered from a drizzle of sharp salsa verde. And a perfect piece of hamachi can reach new heights with the help of some warm, perfectly vinegared sushi rice.
But even when it’s not at the forefront of every bite, vinegar can play a key behind-the-scenes role in building flavor before the stove is even lit. By giving a fillet a vinegar rinse (or even a full-on soak while you prepare the rest of your meal’s components), you can bring out all of the fish’s best qualities and textures, neutralizing any fishy scents while seasoning it. The effect is subtle enough to not impede mild cooking methods, like a quick panfry in olive oil or a gentle steam, but strong enough to add a layer of sweetness and a tender texture to those meaty fillets of icy haddock pulled from the back of your freezer.
Since acidity can denature the fish’s proteins (turning tender, pink raw tuna into opaque, bracingly sour ceviche, for instance), take a lighter touch with smaller, more delicate fish. With mackerel that’s destined for sashimi, or sardines that are destined for a simple oil cure, this means that a couple minutes of marinating is all you need to season the fish while giving it a plumper, firmer texture. (Heartier white fishes like haddock, cod, or even tilapia can take anywhere from 15 minutes up to about an hour of soaking.) This means that you can set your fillets in a baking dish of standard distilled vinegar (or red or white wine vinegar, if that’s what you have on hand) and let them do their thing while you start to set up your dredging and frying ingredients or simmer some water for steaming.
When it’s time to fry, you’ll find that the pieces of fish have a nice integrity to them, which means that they won’t flake apart and dry out the second they hit the hot oil. And believe it or not, the end result won’t taste like vinegar at all—it will just taste like fish, realizing its full potential for greatness.