Bacalao al pil-pil — cod in a garlic and olive oil emulsion

Use cod sold already desalted and ready to cook; it does not need further soaking. Keep it refrigerated until you start. Drain the portions of their packaging liquid and pat thoroughly dry with paper towels, leaving the skin on. Check that no bones remain. Thinly slice the garlic and cut the chili into short pieces. Have ready a wide saucepan or deep skillet about 24 cm across, a fish spatula, a heatproof pitcher and a small metal strainer; choose a pan without a delicate coating for working with the strainer.

Pour all the olive oil into the pan and add all the sliced garlic. Heat gently for about 4–6 minutes, until the garlic begins to turn lightly golden at the edges. Add all the chili for the final minute. Lift the garlic and chili onto a small plate with a slotted spoon; keep them for serving. Take the pan off the heat for about a minute, until the oil stops sizzling noticeably. Do not let the garlic turn dark brown.

Place the fish in the warm oil, initially skin side up. Set the pan over the lowest heat and cook gently for about 5–6 minutes, occasionally spooning oil over any exposed parts of the portions. Carefully turn the fish skin side down with the spatula and cook for about another 5–8 minutes. Small bubbles may appear around the fish, but the oil should not bubble vigorously or fry it until browned; briefly lift the pan off the burner if needed. Cod of this thickness usually takes 10–14 minutes in total and should separate easily into flakes. Pale juices will collect on the bottom; keep them for the sauce.

Transfer the fish to a plate and cover loosely. Take the pan off the burner and leave for about 5 minutes, until the oil is warm but no longer steaming. Let the pale juices settle at the bottom. Spoon most of the clear oil from the top into the heatproof pitcher, leaving all the pale fish liquid and about 1–2 tablespoons of oil in the pan. Add all the juices that have collected on the plate beneath the resting cod to the pan as well. Do not discard anything.

Off the heat, hold the rounded base of the small metal strainer in the liquid in the pan and move it in small circles until the mixture turns cloudy and starts to thicken slightly. Add the oil from the pitcher a teaspoon at a time at first, then in a thin stream, stirring continuously with the strainer. Add each new amount only once the previous one has been incorporated. Work in all the oil over about 5–8 minutes to make an even, pale golden sauce that coats a spoon. If a layer of free oil appears, stop adding oil and let the mixture cool briefly. In a clean small bowl, combine a teaspoon of lukewarm water with a teaspoon of the split sauce, then gradually work the remaining sauce into this base. Use no more than 15 ml water in total; do not add flour or cream.

If you rescued the sauce in a bowl, return it to the pan. Place the cod in the emulsion skin side up and warm over the lowest heat for about 2–3 minutes, gently rocking the pan and spooning sauce over the fish. Do not bring it to a boil, so the emulsion does not split. Add any final juices from the plate as well. Do not automatically add extra salt: desalted cod still contributes some salt to the dish.

Place one portion of cod on each of four plates. Divide all the sauce and all the reserved garlic slices and chili pieces between them. Serve straight away while the emulsion is warm and smooth. The skin remains part of each serving, and all the olive oil is included in the sauce you serve. The recipe does not include bread, potatoes or other side dishes.