Sous Vide Lemon Sole

June 6, 2010

Sous Vide Lemon Sole

Lemon sole is one of the most overlooked beauties among Danish flatfish. Beneath the delicate, almost translucent skin hides firm, juicy flesh with a mild, faintly sweet flavor - far more delicate than, say, turbot or flounder, which it’s often confused with. It’s precisely this fragility that makes lemon sole an obvious candidate for sous vide cooking, where the low, precise temperature protects the fish’s fine structure better than any pan can.

The sous vide method is relatively new in the Danish home kitchen, but its principles land squarely in the respect for the raw ingredient that classic Danish fish cookery has always had. Where fish has traditionally demanded vigilance at the stove - a few seconds too many and the texture turns dry and stringy - the water bath gives full control. Lemon sole is cooked at a surprisingly low temperature, far below what you associate with meat, and the result is a flesh that stays tender and juicy without falling apart.

The fillets are dry-brined briefly before cooking - a simple salting that draws out excess moisture and firms up the flesh a little, so it holds its shape better in the vacuum bag. After a quick rinse, the fillets are cooked at 126°F (52°C) for just 20 minutes, after which they’re ready to serve with no further searing. That makes the dish one of the fastest and gentlest ways to get fish on the table on an ordinary weeknight.

Sous vide lemon sole is best served simply: a sprinkle of flaky salt, a lemon wedge and a little fresh dill or parsley are enough to bring out the fish’s own flavor. For sides, freshly boiled potatoes or a crisp green salad go well with the light dish. For a slightly richer, more rustic finish, the fillets can be browned very briefly in butter after the bag - but the clean version, served straight from the water bath, stays truest to lemon sole’s delicate character.

Ingredients

Serves 4

4 lemon sole fillets, skin and bones removed (about 100-150 g each)
10 g coarse salt, for dry-brining
25 g butter, for pan-frying (optional)
1 lemon, cut into wedges, to serve
fresh dill (or parsley), to serve
flaky salt, to serve

Directions

Pat the lemon sole fillets lightly dry with paper towels. Lay them on a cutting board and salt them generously on both sides with the coarse salt - let them rest for 10 minutes so the salt draws out excess moisture and firms up the flesh a little.

Rinse the fillets quickly under cold running water to remove the salt, and pat them thoroughly dry again.

Set the sous vide bath to 126°F (52°C). Lay the fillets carefully in a vacuum bag in a single layer without overlapping, and seal at low pressure - the fish is fragile and won’t stand up to a hard vacuum.

Lower the bag into the water bath and cook the fillets at 126°F (52°C) for 20 minutes. The fish is very tender and delicate at this point, so don’t exceed the time.

Take the bag out of the water bath and lift the fillets out carefully with a palette knife or a wide spatula. Pat them lightly dry.

Serve at once as they are, with lemon wedges, fresh dill or parsley and a sprinkle of flaky salt. For a lightly golden surface and more buttery flavor, brown the fillets very briefly instead - 30-45 seconds per side - in a very hot pan with butter before serving.

Notes

Lemon sole’s thin, delicate structure is the reason for the relatively high temperature and short time. Related, slightly thicker flatfish such as plaice, flounder and turbot are typically cooked 2-4°F (1-2°C) cooler but 5-10 minutes longer - around 120-122°F (49-50°C) for 25-30 minutes.

Another, more time-consuming version of the dish is the ballotine: two lemon sole fillets are rolled around a filling of smoked herring (bakskuld) and cream, cooked at 108°F (42°C) for 30 minutes, then browned briefly in butter to a golden color. This variant is typically served as a starter and skips salting the fish entirely, since the smoked herring’s own salt content is enough.