Char gives cod with scallion vinaigrette boost

With frozen fish fillets on hand, a meal can be assembled and on the table in short order. The key question is: Defrost, or cook them straight from a solid state?

The answer most often depends on the recipe. When fillets of white-fleshed fish are headed for a soup or sauce or other liquidy endeavor, no defrosting is necessary — and it’s often easier to cut them into chunks while they are still firmly chilled. I find that roasting an inch-thick piece of cod or halibut often goes better when it starts from frozen, too.

For this simple dish, reducing the moisture of the fish will promote browning and help preserve the cod’s true texture as it cooks in the pan. So defrosting is in order.

Cod With Arugula and Charred Scallion Vinaigrette

• 3 thick scallions

• 2 6-ounce skinned cod fillets (no more than 1-inch thick; may substitute halibut)

• Kosher or sea salt

• Freshly ground black pepper

• ½ teaspoon dried thyme (may substitute dried fines herbes or Italian seasoning)

• 2 teaspoons plus 2 tablespoons extra-virgin olive oil

• 1 clove garlic

• 1 lemon

• 2 teaspoons honey

• ½ teaspoon dried oregano

• About 5 ounces baby arugula (may substitute fresh spinach)

Trim the scallions. Thoroughly pat the fish dry with paper towels, then season it lightly with salt and pepper. Crumble the dried thyme between your fingers into a small bowl. Using a fork, whisk in the 2 teaspoons oil, then rub the mixture all over the cod and scallions.

Heat a large saute pan over medium-high heat. Once the pan is quite hot, add the scallions and cook for a total of 3 minutes, turning them over so they are charred all around. Transfer to a cutting board. Add the fillets to the pan and cook until the fish is opaque at the center and just barely flakes under the tines of a fork, 2 to 3 minutes. It should have some nice char or browning. Transfer to a plate.

Chop the scallions into small dice.

Mince the garlic and place it in a large salad bowl. Using a Microplane grater, finely zest the lemon over the same bowl, then cut the fruit in half and squeeze 1 tablespoon of its juice into the bowl as well. Cut the remaining lemon into wedges for serving.

Add the honey and chopped scallions to the bowl. Crumble the dried oregano between your fingers into the same bowl, then whisk in the remaining 2 tablespoons oil to form an emulsified vinaigrette. Reserve some of it to spoon over the fish.

Add the arugula to the bowl with the vinaigrette, tossing to coat evenly. Divide the dressed arugula between plates, then arrange the fillets on or near the salad. Spoon the reserved scallion vinaigrette over the fish and serve right away, with lemon wedges.