Gravlax — Dill-Cured Salmon with Mustard Sauce

Choose a frozen center-cut piece of Atlantic salmon without skin or bones, of an even thickness of about 2–3 cm, yielding 500 g of flesh after thawing and patting dry. The seller must confirm that the fish is intended to be eaten raw and has been professionally frozen to control parasites; an ordinary fresh fillet and home freezing alone do not meet this requirement. Remove the frozen fish from its packaging, including any vacuum packaging, place in a clean dish with a lid, and thaw in the refrigerator at 0–4°C for about 12–24 hours, until the center is soft with no ice remaining. Start curing immediately after thawing, also observing any earlier use-by deadline given by the seller.

Pour off the thawing liquid, pat the fillet dry with paper towels, and weigh out 500 g of flesh. Run your fingers over the surface and remove any remaining pin bones with tweezers. Rinse the dill and dry thoroughly; roughly chop 20 g for curing and refrigerate the remaining 10 g in a separate sealed container for the sauce. Wash your hands and utensils after contact with raw fish, and keep the fillet chilled between these brief tasks.

Mix the salt, 30 g of sugar, and white pepper. Scatter half the mixture and half the dill reserved for curing over the bottom of a glass or ceramic dish that holds the fish in a single layer. Add the fillet and cover with the remaining mixture and dill, pressing them gently onto the top and sides. Cover the dish with a lid and refrigerate immediately.

Cure for 36–48 hours at 0–4°C: for a piece closer to 2 cm thick, start checking the texture after 36 hours; for a thickness of about 3 cm, plan on 48 hours. About every 12 hours, turn the fillet with clean utensils in the liquid collecting in the dish, then immediately cover and return to the refrigerator. The flesh should be noticeably firmer but still supple, with plenty of liquid in the bottom. These are texture cues, not proof of safety: curing does not cook the fish and does not replace prior freezing to control parasites.

Lift the salmon out of the dish and gently scrape off the dill and remaining crystals of curing mixture. Wipe the surface thoroughly with paper towels without rinsing the fish. Pour away all the liquid and discard the removed mixture; do not use either in the sauce. Transfer the cleaned fillet to a clean, covered container and refrigerate while you make the sauce.

Finely chop the reserved 10 g of dill. Mix the mustard, vinegar, and remaining 10 g of sugar in a small bowl, then pour in the oil in a thin stream, whisking vigorously for about 1–2 minutes. When the sauce is smooth, slightly thick, and glossy, stir in the dill. Refrigerate while you slice the fish.

Place the cold fillet on a clean board. Use a long, sharp knife to cut very thin slices across the grain, holding the blade at a low angle to the board to make wide, delicate slices. Use smooth strokes without pressing hard; a firm, chilled fillet is easier to slice without tearing. Arrange the slices loosely on a chilled platter.

Divide the fish and all the sauce into 6 appetizer portions; serve the sauce alongside so it can be spooned onto the slices as you eat. Serve straight from the refrigerator and put out only as much fish as will be eaten immediately. Store any remaining gravlax and sauce separately, covered, at 0–4°C and use within 24 hours of finishing the cure, without exceeding any earlier deadline given by the seller. Do not leave the fish at room temperature for more than 1 hour in total.