1 garlic clove, chopped
2 anchovy filets, roughly chopped
1/2 cup olive oil, plus more as needed
1 Tbsp. sherry vinegar
1/4 tsp. smoked paprika
1/4 cup roughly chopped fresh flat-leaf parsley
Fine sea salt and freshly ground black pepper, to taste
For the fish:
4 (4-oz.) skin-on Atlantic mackerel (also sold as Boston, Common, Caballa or Saba mackerel) fillets
Fine sea salt and freshly ground black pepper to taste
Neutral oil, such as canola or grapeseed, for the pan
2 tsp. freshly squeezed lemon juice
1 lemon, cut into wedges, for serving
Heat the oven to 300 degrees. Arrange the walnuts on a baking sheet and toast until golden, about 10-15 minutes. Let cool.
Pulse the garlic and anchovies in a food processor until combined. Add half the walnuts and process into a paste, about 2 minutes. Add the 1/2 cup oil, vinegar, paprika and process to combine. Add the remaining walnuts and parsley and pulse until there are roughly chopped bits of nuts within the paste, about 1 minute. Season to taste with salt and pepper, adding more olive oil to make a more fluid pesto, if desired. (You’ll use about 1/4 cup of the pesto in this recipe, and you can store the remainder in an airtight container in the fridge for up to one week.)
Score the skin of the mackerel fillets and trim off any remaining belly bones. Season the fillets to taste with salt and pepper. Chill and let rest for 15 minutes before cooking.
Place the oven rack in the top position and heat the broiler. Line a baking sheet with aluminum foil. Rub a very thin layer of oil on the foil. Lay the fillets on the prepared sheet, skin side down, and sprinkle with lemon juice. Spread a thin layer of walnut-parsley pesto on each fillet and broil until the fish is just opaque at the center and the surface is browned, rotating once, about 6 minutes total. Serve with the lemon wedges. Serves 4.
— From "Bon Appétit: The Food Lover's Cleanse" by Sara Dickerman (William Morrow, $35)