Shopping for fish can be intimidating. Maybe it’s the fact that half of them are staring at you from behind the counter, as if to say, “Jeez, how did I end up here?” So, if you’re going to do them—and yourself—justice, here’s how to rustle up a fine, fresh fillet. You need to use your eyes and your nose. Look for a cut where the flesh is moist and glistening, with no flat, brown edges. If the fish looks dull, take a pass. Same goes for any fillet with a fishy or ammonia smell. Don’t be shy about asking your fishmonger a few questions, like when the fish came in and from where. Most stores have regular shipments; knowing that schedule in advance can help you plan when to have fish. If black cod were in a band, it would be the bass player: steady, meaty, but not much of a soloist. It benefits from some jazzy front men and especially likes to swing with citrus high notes. You’ll find plenty of those riffs in this dish.
1/2 cup freshly squeezed orange juice
2 tablespoons freshly squeezed lime juice
2 tablespoons freshly squeezed lemon juice
1 tablespoon extra-virgin olive oil
Zest of 1 orange
Zest of 1 lemon
1/2 teaspoon minced fresh ginger
Pinch of cayenne
4 3.5-ounce black cod fillets, pin bones removed
1/2 teaspoon sea salt
1 teaspoon Dijon mustard
1/4 cup coarsely chopped fresh flat-leaf parsley or mint
COOK’S NOTE: This versatile, delicious marinade is great with other fish, such as sea bass, salmon, and halibut. These flavors also pair nicely with Warm Napa Cabbage Slaw (page 92). You can also cook the fish on a grill. Wipe the marinade off the fillets and rub them with 1 teaspoon of light sesame oil. Grill over low, even heat for about 4 minutes per side, until the flesh is opaque and flakes easily and the center of each fillet registers 137°F.
In a small bowl or glass measuring cup, whisk together the orange juice, lime juice, lemon juice, olive oil, orange zest, lemon zest, ginger, and cayenne. Place the cod in a baking dish and season each piece with 1/8 teaspoon of the salt. Pour half of the orange juice mixture over the cod and turn to coat well. Cover and marinate in the refrigerator for 30 minutes.
Preheat the oven to 400°F.
Remove the cod from the refrigerator, uncover, and add 2 tablespoons of water to the bottom of the dish. Bake just until the fillets are tender and an instant-read thermometer inserted into the center of each fillet registers 137°F; it will take 10 to 15 minutes, depending on the thickness of the fillets.
Meanwhile, combine the remaining orange juice mixture and the mustard in a small saucepan over medium heat and simmer until the liquid is reduced by half. Pour the reduction over the fillets, sprinkle with the parsley, and serve immediately.
STORAGE: Store tightly wrapped in an airtight container in the refrigerator for 1 to 2 days.