Sous Vide Bacalao Pil Pil

Cooking the Bacalao sous vide allows us to use much less oil than our previous modernist approach, while perfectly cooking the fish and capturing the essential gelatin that gives us the Pil Pil emulsion.

Bacalao with Pil Pil sauce, Catalan style greens, Pa amb tomàquet

Previously, we'd used the science-based technique we learned from Basque chefs: they completely submerged the Bacalo in enough oil to cover and gently cooked to release the gelatin required for this sauce. This is much less work and much more reliable than the traditional method of sliding the fish back and forth in a pan with a little oil to release the gelatin, but it left us with a huge amount of fishy oil that we had to find a use for.

This time, we reasoned that we could use much less oil if we cooked the fish in a sous vide bag, and it would be trivial to capture the released gelatin.  It would also allow us to cook the fish very gently in a controlled manner.

We had gotten a big frozen chunk of skin-on, bone-in Bacalo from a Portuguese market. We believe it was salted like traditional Bacalao but it had been rehydrated to desalinate before freezing.

370 g     Bacalao (rehydrated to desalinate)
4   clove Garlic
1         Chili Arbol, seeded
250 ml    Olive Oil, good quality
1   pinch Salt

Seal Bacalao, Garlic, Chili, and Olive oil in sous vide bag.

Cook sous vide at 78C/172F for 30 minutes. When you remove the bag from the bath, you should see the white liquid gelatin below the fish and oil.

White gelatin elixir below Bacalao, oil

Pour off the liquid into a tall narrow container and allow to separate. Use a turkey baster to extract the gelatin from the bottom to another tall narrow glass. Repeat separation until you've got one container of oil and one of gelatin; it's all right if it's not perfect.

First settling

Second separation, mostly gelatin; oil is in the bowl on the right

To make the Pil Pil sauce, add 10-15 ml (2-3 tsp) of the white gelatin liquid to a pan and turn on very low heat.  Whip to incorporate air; I used a mesh scum skimmer which worked very well, but a fork or whisk should also do.  When frothy with fine bubbles, drizzle in a few drops of the oil. Continue whipping until a stable emulsion forms. Add more oil, a little at a time, and incorporate until you have the volume you need. If the emulsion starts to break or if it becomes too thick for your taste, add a splash of hot water and whip to incorporate. I took the pan off the heat and did most of this on the counter, as it seemed even the low heat was encouraging the sauce to break. Adjust taste with salt.

Whisk oil into gelatin with mesh skimmer to form emulsion

Plate cooked fish, and top with Pil Pil sauce.  We served ours with mustard greens cooked Catalan style with sultanas, toasted pine nuts and garlic; and Pa amb Tomàquet (toasted bread rubbed with garlic and topped with -- in our case -- tomato pulp instead of being rubbed with fresh tomato).

Save the rest of the precious gelatin; we froze ours.

What Worked, What Didn't

Everything worked beautifully with this technique: we got a bunch of precious fish elixir to use and to save for a future batch; we didn't end up with liters of excess fish oil; the fish was nicely cooked, and the Pil Pil sauce had a good texture.

Now that we've figured this out, a simple search shows us we are not the first to do it this way; duh.

Next Time

How low can we drop the heat and still extract the gelatin elixir? 78C seems a bit high to cook fish, can we drop it to 55C/131F where the gelatin is supposed to first start releasing? Does Bacalao need the higher temperature? Would other fresh (unsalted/rehydrated) fish be better at lower temperatures? One recipe we found recipe uses 65C/150F for 30 minutes.

Try traditional dry salted Bacalao; we have noticed that none of the boneless pieces had skin on, and the skin may be where all the gelatin lives.

Since we use so little oil and there not much effort, we can try other fish species; we've already ascertained Mahi Mahi works (and Sea Trout did not). What others will release gelatin for an emulsion?

Other Work

In 2022 we recreated this in our Barcelona apartment, at 55C for 30 minutes but pointed out 45-60 might be better. 

While looking for other sous vide bacalao recipes, I found two videos which provide more ideas. 

This first, which was done in 2015 and therefore predates mine, cooked at 65C for 30 minutes, and used the same strainer-in-skillet technique I did to create an emulsion from the "fish water", what I called "elixer. 

The next, from 2021, streamlines it even further: she cooks the fish sous vide at 60C for 20 minutes, but without adding any oil. She then drains off the fish liquid elixir into a cup, no oil separation required, and creates the emulsion with a stick blender, adding in the garlic-oil to build the sauce -- brilliant. She adds a bit of honey to each bag.

This one from 2020 is nearly identical, but he cooks at 48C for 20-30 minutes before emulsifying the fish liquid with a stick blender, then adding oil. He cooks the garlic in oil in a jar in the same bath as the fish, so he doesn't even need a sauté pan. He adds some membrillo to each bag.