Mahi Mahi Pil Pil #2 sous vide: lower temperature, less oil

We discovered that Mahi Mahi releases the emulsifier (like Bacalao) that builds the creamy Pil Pil sauce. This time, we'll try lower fish-friendly temperature and less oil, since the sauces expands like a mayonnaise. We're using sous vide again to control the temperature and minimize oil; this turned out very well.

Mahi Mahi with Pil Pil sauce, served with asparagus and patatas bravas

Our previous work with Bacalao and Mahi Mahi used temperatures from 90C/194F down to 65C/150F, and this time we'll go to 60C/140F.  We got a vacuum packed pair of filets, skin on; we believe the emulsifier is under the skin, but cannot prove it. We freeze a bit of oil, and vacuum bag it with the fish, traditional garlic and chili. It doesn't take long, about 30 minutes.

312 g       Mahi Mahi, as 2 skin-on filets
100 ml      Olive Oil
  4 cloves  Garlic
  2 whole   Chili
            Salt

Put 50 ml of Oil into 2 bowls and freeze hard so it doesn't get sucked out when vacuuming the bag.
Chill the filets of fish in the freezer so they won't lose water when vacuuming, or leave frozen if they came that way.
Use two vacuum bags, and place a filet in each, with a frozen Oil puck, 2 cloves Garlic, 1 Chili each; seal.

Cook the bags in a sous vide bath heated to 60C/140F for 30 minutes.
Strain off the oil into a tall narrow container like a skinny glass: you hopefully should have some white proteins, the precious emulsifier; let it settle out and slurp the protein into a small bowl or glass with a turkey baster.

Note the protein, the emulsifier, settling to the bottom

Building the emulsion

Leave the fish in the bags, hanging in the water to keep warm for service.
In a warm skillet, whisk the protein to whip in air; after a while -- about 5 minutes -- it should start foaming.
Drizzle in some of the fishy oil, a little at a time, and whip until you form an emulsion.

The sauce has incorporated most the oil and come together beautifully

Continue adding oil and building the sauce; if it starts to thicken, whisk in some warm water; season with salt as you whisk. We used all the oil from the bags and it made a proper amount.
Plate the fish, top with the sauce, add the garlic and chili as a garnish.

Results, Next Time

The texture of the fish came out well at this low temperature, but the thicker piece could have used a little more time under the skin. 

The skin on this fish was a distraction, it was soggy but a bit chewy; next time, remove the skin while the fish is raw but put it in the sous vide bag because we believe that's where most of the emulsifier is. (I think it would be more difficult to remove the skin after cooking, as the fish is fragile, and it would cool down.)

This was a perfect amount of Pil Pil sauce, so the reduced oil was the right proportion.

Consider adding some lemon juice to the Pil Pil in addition to the water too give it some zing; maybe this violates some Basque law...