Chef Michael Cimarusti on slowly roasting a fish fillet

When I’ve got a big group of friends coming over for dinner, I’ll usually prepare a roast. Frankly, I’ll do the same thing even if I’m cooking only for our family of four. First, preparing large roasts is easier than cooking several individual portions. And a well-rested and properly cooked roast is a delicious thing. Then, of course, bringing a big roast to the table is great theater. (Ever hear of Lawry’s? Yeah, I thought you might have.)

Here’s the catch: That roast had better be perfect. Present a roast that winds up being medium-well when sliced and your next dinner party will be more intimate than you might prefer. To make sure my roasts are exactly as done as I want them, I use a slightly different technique than you might be used to.

Even better, it works perfectly for fish. And nice as a standing rib roast might be, a perfectly roasted whole fillet of salmon, white sea bass or swordfish is really something special.

Where to begin? Well, at the fish market, of course. You’re looking for something wild, sustainable, meaty and large. Start by asking for local white sea bass, California swordfish, Pacific king salmon or wild striped bass from the East Coast. Allow 6 to 8 ounces of fish per guest, and ask your fishmonger to give you the top half of the fillet.

Fillets from large fish have two distinct halves: top and bottom, or back and belly, you might say. You’ll want the top or back loin. If you’re cooking swordfish, you’ll just need a nice long piece of the loin. You can ask the fishmonger to leave the skin on or you can have it removed. If he’s already removing the skin, ask the fishmonger to remove the bloodline as well.

Before cooking, brine the fish in a 5% salt solution for an hour. Then pat it dry and hold it in the refrigerator for at least six hours or overnight before cooking to set the surface of the meat.

An hour before you’re ready to cook, remove the fish from the refrigerator and allow it to come to room temperature. At the same time, heat your oven to 300 degrees.

When you’re ready to cook, gently heat a pan large enough to hold the fillet. Season the fillet with sea salt and Espelette pepper. Add olive oil to the pan along with butter. When the butter begins to foam, add the seasoned fillet along with garlic cloves and thyme, which will flavor the butter and the fish at the same time. (Incidentally, the butter, with the addition of a little lemon juice or vinegar, makes for a great simple sauce.)

Be sure the pan doesn’t get too hot. Watch the color of the butter; it’s a great indicator of temperature. Too hot and the butter will brown too quickly and burn; too cold and you’ll get no color at all.

As the temperature of the pan rises, lower the flame to moderate the heat. After two or three minutes carefully flip the fillet over. Cook the second side for an additional three minutes, basting with butter while it cooks. You are not looking for dark color. If the fillet browns too deeply, the pan is too hot and the fillet will be tough.

Remove the fillet to a rack set on a baking sheet. Let it rest for three minutes, then check the internal temperature at the thickest part of the fish using a thermometer. Depending on the thickness of the fillet and the temperature of your kitchen, you will most likely find the internal temperature is around 100 degrees.

Brush the fish with a little softened salted butter and place the fish in a 300-degree oven for three minutes. Remove it, rest the fish for three minutes and take the temperature again. You get the point. Roast and rest the fish in three-minute intervals until it reaches 118 degrees.

If you think this process seems a little obsessive, well, you’re right. But it delivers, and that’s the point.

In fact, I use much the same technique when I’m roasting meat. You just stretch out the roasting and resting times to, say, 20 minutes on and off for something like a standing rib roast.

Will it take a bit longer than blasting the roast at a constant 450 degrees? Yes. Will the results be much better? Absolutely.

Cimarusti is the chef and owner at Providence and at Connie and Ted’s.

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