Preheat the sous vide bath to
183 F/84 C.
Cut the celery, carrots and scallions into thick strips approximately 3″/75 mm long, also known as “batonnet.”
Stage the vegetables into a dedicated vacuum bag and seal. Add to the preheated bath and set a timer for one hour. Meanwhile…
Stage each individual trout into a dedicated vacuum bag. Add 1 oz/30 ml of the vinegar and 1/2 teaspoon of salt to each bag and seal. Set aside until the timer goes off.
After the hour has passed, add the fish to the tank and turn off the heat. Set the timer for 10 minutes. After the time has elapsed, remove the vegetables and the fish from the bath.
Cut off a small corner of the bags with the trout and the vegetables and drain the liquid into a small sauce pan. Stage the vegetables into a dish and keep warm.
Reduce the liquid until you have no more than 1 oz/25 ml. While the broth reduces, cut the cold butter into six pats. Add the pats of butter one at a time, swilling the pan as each pat of butter melts, adding one pat at a time. It is not really necessary to use a wire whisk, but some people find it helpful. The temperature of the butter sauce should not go below 160 F/70 C. After the last pat of butter has melted, pour the sauce into a plastic squirt bottle or goose neck. Set aside.
Remove one of the fish from its bag. Place it on a plate as depicted above, with the back facing you.
Use a spoon to remove the head. Use a knife to make an incision from head to tail, ABOVE the dorsal fin.
Turn the plate around and use the spoon to remove the visible fins from the belly and near the tail…
Gently grab the skin at the corner and pull. Expert waiters can remove the skin in one piece, but it is not really necessary. It is worth giving a try though. It never seems to work when someone is watching!
Use the spoon to draw a line down the visible seam. Remove the dorsal fin. Use the spoon to push the upper and lower halves away from the backbone.
Grab the backbone at the largest end and lift, pulling it towards the tail. Take your time.
Don’t worry if it gets a little torn up. Expert waiters will no tell you that a little butter sauce and some chopped parsley does wonders…
With a little practice and a little luck, the backbone will come out in one long piece, removing most of the bones with it.
If bones remain, they will be the fine rib-cage pin-bones nearest the head. They can be troublesome–one should never expect a fish to be completely boneless, even in the finest of restaurants.
Gently fold the upper and lower halves back on to the fish, or leave open–both presentations are perfectly acceptable.
Place a few of the vegetables on the plate as shown and sauce the fish liberally. Chopped parsley, of course!
It looks even better up close.
If you love capers as much as I do, sprinkle a few on top as well.
So simple, and yet so appealing!
I must confess, I do not typically process seafood using sous vide. Fish proteins are very fragile, and sous vide tends to “tenderize” them whether they need it or not. Applying a crust after processing usually takes as long as it would just to cook the fish in the pan in the first place. Even so, there are a few fin fish that sous vide works well with–trout, of course, and salmon. I find flatfish like halibut and Dover sole just too delicate. It is even difficult to remove them from the bag. There is no accounting for taste!