Bacalao Pil Pil Sous Vide -- in our Barcelona apartment

In our last episode with Bacalao, we found that we could get the "elixir" -- the emulsifier for the pil pil sauce -- efficiently using minimal oil using a sous vide technique, and subsequent experiments showed we could even do this with Mahi Mahi, at lower temperature.

We recently moved to Barcelona, where Bacalao is everywhere, and  restaurants have special machines to agitate the fish in oil to create the emulsion. We brought our first-generation sous vide machine by Sansaire -- even though it only ran on US-style 115VAC 60Hz: we got a step-down transformer to convert Spain's 230VAC to 115VAC, and hoped the 50Hz frequency wouldn't bother the motor too much. 

Tonight's dinner proved a success, using local bacalao and the hacked sous vide setup. We also discovered that using a even lower temperature works, and have suggestions for improvement.

Bacalao with emulsived sauce, served with potatoes and bulbing onions from the plancha

For a previous dinner here, we got some salted, dried bacalao from our local supermarket. The person in front of us got all coveted loins ("Estalvi!",  "saving!"), so we picked up a couple filets. We rehydrated them over a couple nights in the fridge and used half of it for one dinner, and froze the rest which we used tonight. The proportions below are what we had, and what we did; in the epilog, we suggest adjustments.

280 g      Bacalao filets, skin on, hydrated
pinch      Cayenne pepper flakes
2 cloves Garlic, sliced
120 ml    Olive Oil and Corn Oil mix (we ran out of Olive Oil)

Bag everything in a zip-top and place in a sous vide bath at 55C/130F for 30 minutes. I turned and agitated the bag every 5 minutes or so to make sure everything was distributed well.

How embarrassing: 135F, not 55C

Pour the oil and the critical milky white liquid that collected in the bag, the "elixir" (which I believe is a weak gelatin from under the skin of the fish, or at least in its flesh) into a tall glass and let it settle out. Use a turkey baster to pull the milky liquid from under the oil and put in a pan on medium heat.

Keep the bacalao in its bag in the still-hot water bath, with the power turned off, so it stays warm for service.

Use a stock skimmer or similar to whip air into the elixer. This time, mine was quite thin, so I had the heat on our induction cooker high enough to barely simmer the liquid to reduce it a bit. Bubbles begin to form as I whisked air into it, and after a while, I bravely added some of the reserved oil: it started to combine into an emulsion -- success! I continued whisking and adding oil to build the emulsion and developed one as thick as mayonnaise, so I added a bit of lemon juice and wine, and a dash of salt, and finished when I'd used all the oil. 

Thickened emulstion 

Plate the fish, top with emulsified sauce and sliced garlic from the bag, and serve. Some parsley would have helped here.

Results

I was happy to see the milky white "elixir" in the bag after about 15 minutes, but when I poured it into the pan, it seemed really thin. It appeared to be the hydrating water from the bacalao, and I was worried it wouldn't turn into an emulsion. But after bumping up the heat to a bare simmer and continuing to whisk, it did thicken a bit and bound the oil just fine.

The fish was a bit salty, which was a result of under-hydrating the dried bacalao, not this process.

The flesh of the fish flaked, like you'd expect cod to do, but required just a bit more force than I'd like. It was still moist, so reducing the temperature from 60C/140F to 55C/135F was a good move -- and we still got the elixir. 

There was more emulsified sauce than we needed for the fish, and it was quite thick despite thinning with wine and lemon juice. It complemented the potatoes Irene cooked on the plancha quite well, so nothing was wasted.

Next Time

When hydrating dried bacalao, take a sample, cook it, check the saltiness, and hydrate longer if needed; don't over hydrate or it will become bland. Ours was too salty but by this point it was too late to adjust. Our fish mongers will helpfully hector us about the right duration to hydrate and the number of changes of water we need: listen to them, and test for taste!

Keep the cooking temperature at 55C to preserve the moistness, but increase the time from 30 to 45 or maybe 60 minutes to allow it to flake more easily.

Cut the oil for the emulsion in half, 50-60ml should do. The wine, lemon, and salt were fine additions, so keep them, but taste, taste, taste for balance.