Merluza en salsa verde con almejas, or hake in green sauce with clams, is a classic dish from the Basque Country in northern Spain. Fish fillets are gently simmered until flaky in a parsley, garlic and olive oil sauce, then are finished with cooked clams in their shells. At the seaside restaurant Txoko Getaria, we tasted an especially delicious version in which the oceanic notes of the fish and clams were in perfect balance with the fresh flavors and luxe character of the sauce. Txoko takes a nontraditional, multistep approach to preparing the dish: the fish is parcooked on the grill and the sauce is made by stirring a fragrant pesto-like blend of parsley, garlic, almonds, olive oil and Idiazabal cheese into a base comprised of flour-thickened, oil-and-garlic-enriched fish stock. We adapted their formula and devised a method that requires only a food processor and a skillet but yields delicious results in only about an hour. The cubanelle pepper (or jalapeño chili) in our recipe is a stand-in for hard-to-source Basque guindilla chilies. And if you cannot find Idiazabal cheese, a Basque sheep’s-milk cheese with a subtle smokiness, manchego is a good substitute. Either skin-on or skinless fish fillets work here, but try to choose pieces that are uniformly about 1 inch thick.