If I had to name three kitchen skills I wish more home cooks endeavored to master, they'd be: learning to work more cleanly, cutting more efficiently (and safely), and knowing how to crisp the skin of a piece of fish. That last one is a lot more specific than the other two, but I rank it just as highly because it's one of those tasks that demonstrates real kitchen finesse. The ability to take a protein that's incredibly moist, tender, and delicate and make part of it unbelievably crunchy, like a potato chip—without ruining the rest of it in the process—is quite a feat.
If that sounds daunting to you, you're not alone. Trying to pan-roast a crisp-skinned fish is, based on my incredibly unscientific and anecdotal experience, something that most home cooks don't ever attempt. They should, though, since it's not nearly as difficult as it seems. Plus, once you get the technique down, it's one of the quickest ways to put a delicious protein on the dinner table.
The key to the whole process is learning to control both heat and moisture. Get those parts down, and you'll be marveling at your crisp-skinned fish in no time, no matter if you're cooking snapper, salmon, or bass.
Step 1: Dry the Fish Skin Very, Very Well
Fish is moist, and that moisture actively works against your efforts to crisp its skin—in order for that to happen, the skin has to dehydrate first, which takes a lot of energy. Any water we can remove from the skin before it ever hits the pan gets us ahead by leaps and bounds, since it's that much less water that needs to be driven off in the pan.
There are two things I like to do to dry the skin. The first is a technique I think I first learned from Thomas Keller, in which you use your knife more or less like a windshield wiper, gently dragging the blade across the skin. Liquid will collect on the knife's edge as you literally scrape it from the skin; wipe it up with a paper towel every few passes, then go back and scrape some more. I do this over and over until the knife comes up dry with each pass. Just be careful not to press too hard. Fish is delicate, after all, and you don't want to smash it.
The second thing I do is pat the fillets dry with paper towels. If you've done a good enough scraping job, the towels should come up bone dry, but it's still worth making sure.
If you have whole fillets, it's easier to do the drying before portioning them (as pictured in the photos here), but it's not required.
Step 2: Choose Your Pan
The understandable temptation here is to grab a nonstick skillet. I won't be so strict as to tell you to absolutely not do that, because it's possible to get decent results with nonstick. But you won't get the crispest skin.
If you really want to ace this skin-crisping thing, you have to let go of the security of nonstick and grab a skillet that carries the risk of sticking. Your best option is either cast iron or carbon steel, both of which, when seasoned properly, offer some nonstick benefits. Even stainless steel, which isn't even remotely nonstick, works when you use the right technique.
In the photo above are three pieces of snapper, which I cooked in three different skillets over the exact same heat setting on an induction range. As you can see, the cast iron and stainless steel (at left and middle in the photo) produced very similar results; I'd say they're just about equal. The nonstick (at right) was close, but the skin wasn't quite as crisp as it was with the other two.
You'll notice that the nonstick sample has some holes burned through the skin. That may have been because I was using a large nonstick skillet with just one small piece of fish, and the pan may have overheated. (The other skillets were heated on the exact same heat setting, but they were slightly smaller.) But that leads me to another big problem with nonstick, which is that it's not at all a good idea to use it for high-heat cooking: The nonstick coating can deteriorate, eventually producing toxic gases, if allowed to get too hot.
Step 3: Get the Oil Smokin' Hot, Then Take a Tentative Dip
Okay, so far we have a nicely dried piece of fish and an appropriate skillet. Next up, we need to put oil in that skillet and get it very, very hot. I'm talking full-on shimmering, with the first few wisps of smoke.
Why? Well, the main reason fish and other meats stick to pans is that, when raw, the proteins literally bond with the metal. For something like chicken or a steak, the meat is robust enough that even if it sticks, you can work it free without doing any real damage. Not so with fish. It's so delicate that if it fuses to the pan, there's a good chance the whole thing will tear to shreds as you try to free it.
Once cooked, though, the proteins are much less inclined to bond to the metal. The key, then, is to cook those surface proteins so rapidly that they're fully transformed before the fish touches the pan. As thin as a layer of oil in the pan is, if it's hot enough, it'll do just that.
When the oil is hot, I quickly season the fish all over with salt and pepper, then get ready to lower it, skin side down, into the pan—but I don't just drop it in. Instead, I like to test the waters first...or, I guess I should say, I like to test the oils. Without letting go of the fillet, I drag the fish across the surface of the pan, feeling for whether it's sticking or not. If the pan and oil are hot enough (and, in the case of cast iron and carbon steel, if the pan is well seasoned enough), the fish should glide across like a skater on ice. It's only when I'm sure it's not catching that I lower it into the pan, always away from myself so that the oil doesn't splash onto me.
If I do feel the fish stick, I abort the maneuver. With cast iron or carbon steel, I usually take this as a sign that I need to season the pans better. The best way to season a pan is by repeatedly rubbing it with an incredibly thin layer of oil and letting it heat each time in the oven to build up a good layer. In a pinch, though, you can also swirl some oil in the skillet, let it reach the smoke point right over a high flame, then wipe it out and repeat. This is usually enough to season it sufficiently so that the fish won't stick at all.
Of course, seasoning isn't relevant when it comes to stainless steel, but if you've dried your fish well and heated the oil enough, you shouldn't have any issues—it should still be able to glide across the pan. As you can see in the photos above and below, I'm able to slide the fish across without it clinging to the pan.
Now you can let go!
Step 4: Press It Flat
Skin-on fish will almost always curl when it hits the pan. This is largely due to the skin itself contracting as it comes into contact with the heat, though, in my experience, the degree of curling is related to the freshness of the fish. The fresher it is, the more it seizes up.
There are a number of tricks for dealing with this. Some folks like to start it flesh side down for a quick minute, just to set the meat a little, then flip to the skin side. This can reduce curling, but it also means you'll be putting the skin into a pan that's lost some heat, which can increase the chances of it sticking. I prefer to just take a slotted spatula and gently press down on the fillets to flatten them out. Only press down enough to get full contact between the skin and the pan; any harder, and you risk mashing the fillet.
The slotted spatula, by the way, is an essential tool here. It's thin and flexible enough to slide under the fish without crushing or otherwise bulldozing it.
Step 5: Manage the Heat (and Hands Off!)
Aside from pressing the fish flat, you should otherwise resist the urge to touch it. Even though all the prep we've done thus far should reduce the amount it will stick, it may still stick a little at first. If you try to lift it too soon, you could end up tearing the fish.
Meanwhile, you'll want to start regulating the heat. We needed the oil extra hot when the fish first hit it, but we don't necessarily want to keep the heat cranked up the rest of the time, lest we burn or overcook the fish. It's safe to lower the heat now to a more moderate level—not so much that you lose the sizzle, but not so little that it scorches, either.
After a minute or two, you should be able to see some browning around the edges as the heat creeps up through the fillet. If it's an especially thick fillet (more than an inch and a half or so)—and not something like salmon that you'll be serving medium-rare—you can transfer the skillet to a 350°F oven so that the heat cooks it through from above and below. If it's thinner, like the fish pictured here, you can do the whole thing on the stovetop.
Most of the cooking can happen with the fish skin side down. Not only will the skin become more crisp the longer it's in contact with the pan, but it also acts as an insulator, protecting the delicate flesh from becoming tough and dry. It's only time to flip the fish when it's nearly cooked through. (If it's in the oven, it will have cooked from above as well, ensuring that you don't have a big hunk of raw fish on your hands.)
Step 6: Master the Timing and Technique of the Flip
When it's time to flip, carefully slide your spatula under the fish while pressing it firmly against the skillet, just as you might slide a razor blade under a sticker that's refusing to peel off. If you feel resistance, don't just brute-force it. Instead, delicately try a few different approaches to see which one gets you fully under the fillet without damaging the skin.
If all goes well, it won't be hard to do at all, and the fish should come free and slide around the skillet without trouble. Then just flip the fish over and give it a quick sear on the other side to finish it up.
Master this technique, and I guarantee you'll be whipping it out every chance you get.