Bacalao al pil pil is routinely presented as the cod dish of northern Spain, as if one recipe stretched unbroken from the Bay of Biscay to the Ebro. It does not. Pil pil belongs to Bilbao and the Biscayan coast, and Pamplona never claimed it. Navarra’s capital has its own salt cod tradition, ajoarriero, and the two dishes are built on opposite ideas of what a piece of cod is for.
That distinction is worth getting right, because it explains what you will actually see on menus. Travelers who arrive in Pamplona expecting the glossy yellow sauce of the Basque pil pil find shredded cod stewed with peppers instead, and assume the kitchen took a shortcut. It did not. It cooked the inland dish, the one that history put on Navarrese tables. Order either one knowingly and you eat better in both cities.
This article draws on the Basque press that has examined the dish’s origin legend, on the chemistry that Spanish chefs themselves cite when they explain the sauce, on the fishery scholarship archived at the Universidad Pública de Navarra, and on the documented record of the Bilbao houses that still serve the dish daily.
Four Ingredients, One Technique
Bacalao al pil pil contains salt cod, olive oil, garlic, and guindilla chili. Nothing else. The garlic is sliced and gilded in olive oil, the pan comes off the heat, and skin-on loins of desalted cod go in. Cooked slowly at low temperature, the fish releases its juices and dissolved gelatin into the oil, and the cook swirls the pan in a steady circular motion until fish juice and oil bind into a thick, pale gold emulsion. The sauce is not added to the cod. The sauce comes out of the cod.
The name is onomatopoeia. As the loins warm, the oil gives a soft, rhythmic sputter, pil pil, pil pil, as connective tissue breaks down and moisture meets hot fat. In Euskara the dish is called bakailaoa pil-pilean, and you will see both forms on menus around Bilbao. The skin matters more than any other single choice: most of the collagen that makes the sauce possible is concentrated in and just under it, which is why a skinless fillet produces cod in plain oil rather than pil pil.
The Telegram Legend and the Real Gurtubay
Ask in Bilbao where the dish comes from and you will hear the same story. In 1835 a merchant named Simón Gurtubay ordered “100 o 120” dried cods from his supplier. The order was garbled in transmission, and instead of a hundred odd bacaladas he received a ruinous mountain of them, over a million in the most popular telling. Then the Carlist army besieged Bilbao, food ran short, and the city survived on Gurtubay’s surplus cod cooked with the two things nobody had run out of, garlic and olive oil. The siege lifted, the merchant was rich, and pil pil was born.
It is a wonderful story, and the Basque press has repeatedly shown it does not hold up. The Bilbao daily Deia calls it a fábula: the versions contradict each other on the quantity, the date, and even the decade, and no document supports any of them. Historians add the obvious problems. Bilbao was already Spain’s principal port of entry for salt cod long before the Carlist Wars, cod dishes such as bacalao a la vizcaína already existed, and the garbled telegram motif sits awkwardly in a Spain that had barely strung its first lines. The siege of 1835 and 1836 was real, and cod certainly fed the besieged city. The rest is embroidery.
Gurtubay himself was real, and his actual biography is better than the myth. Born to laborers, he began as a shoemaker, built one of Bilbao’s great import houses bringing cod from Norway, Scotland, and Iceland, and by 1866 sat as an adviser at the founding of the Banco de Bilbao. Salt cod made fortunes in that city for a century. It did not need a lucky typo to do it.
The Fifteen Degree Window
What separates pil pil from every other way of cooking cod is chemistry, and Spanish chefs talk about it in exact numbers. The collagen in the cod’s skin and connective tissue converts to gelatin at low temperature, and that gelatin is the emulsifier. It plays the same role lecithin plays in mayonnaise, wrapping microscopic droplets so that oil and the cod’s own water, two liquids that want nothing to do with each other, hold together as one thick sauce.
The window is narrow. Working chefs interviewed on the technique agree that the emulsion forms between 55 and 70 degrees Celsius. Below that, the gelatin never releases from the fish. Above it, the water evaporates, the gelatin degrades, and the cook is simply frying cod while the sauce splits back into greasy oil. The traditional method manages that window with nothing but wrist and patience, a continuous gentle swirl of the cazuela that can take twenty minutes or more. Many modern kitchens lift the cooked loins out and whip the warm oil and juices with a fine strainer, which produces a stable sauce in two minutes. Traditional houses consider that a different dish, bacalao ligado, sauce and fish bound together in the pan from start to finish rather than assembled afterward. Both appear all over the Basque Country. Only one of them makes the sound the dish is named for.
Coast Versus Interior: Pil Pil and Ajoarriero
Here is the part the recipe sites skip. Spain’s salt cod map is not one tradition, it is two, drawn by geography. On the coast, in Bilbao and the fishing ports of Biscay, cod arrived whole and abundant off the boats, so the cooking celebrates the intact loin: pil pil, vizcaína, big white flakes under sauce. Inland, cod arrived on the backs of mules, sold by traders who hauled preserved fish to towns that would never smell the sea. Those muleteers were the arrieros, and the dish named for them, bacalao al ajoarriero, shreds the cod and stews it with peppers, tomato, garlic, and potato, stretching an expensive preserved fish across a whole table.
Pamplona sits firmly on the inland side of that line. Ajoarriero is Navarra’s cod dish, the one with centuries of local standing, and during San Fermín it is ajoarriero, not pil pil, that anchors the cod section of traditional menus. Salt cod conquered inland Spain in the first place because the Catholic calendar demanded fish on days of abstinence, and preserved cod was the only fish that could travel that far. The supply chain behind all of it ran through Basque and Cantabrian ports, the same waters that produce the anchovies of the Cantabrian coast, and in the twentieth century it stretched all the way to Newfoundland: the standard study of the Terranova cod fleet, archived at the Universidad Pública de Navarra, documents Spanish crews working those banks from 1926 to 2004.
So the honest framing is this. Eat bacalao al pil pil in Bilbao, where it was born and where the loin is the point. Eat ajoarriero in Pamplona, where the shred is the point. Neither is a lesser version of the other.
Where It Is Actually Served Today
The dish’s home institutions are Bilbao’s old dining houses. The clearest example is Restaurante Víctor, open on the Plaza Nueva since 1940, which has built its reputation on cod served three ways: pil pil, vizcaína, and bacalao al estilo Víctor, the house creation that finishes a pil pil with crushed tomato. The city’s tourism office lists the house among Bilbao’s essential traditional tables, and the local press still writes up its pil pil by name. Across the Casco Viejo of Bilbao, the dish remains an everyday order rather than a museum piece.
In Pamplona you will find pil pil on the menus of asadores and traditional dining rooms in the old city, usually sharing the cod section with ajoarriero, and a glass of txakoli alongside is the natural coastal pairing. But watch what the tables around you order during fiesta. The shredded dish wins in its own city, as it should.
Frequently Asked Questions
What is bacalao al pil pil made of?
Four ingredients: salt cod (desalted before cooking), olive oil, garlic, and guindilla chili. The sauce contains nothing else. It is an emulsion of the olive oil with the gelatin and juices the cod releases as it cooks slowly at low temperature. There is no flour, butter, cream, or egg in a correct pil pil, and skin-on loins are essential because the skin holds most of the collagen that binds the sauce.
Why does my pil pil sauce not thicken?
Temperature is almost always the reason. The cod’s gelatin emulsifies between roughly 55 and 70 degrees Celsius. If the oil is too hot the fish fries and the sauce splits; too cool and the gelatin never releases. Use skin-on loins of good salt cod, keep the oil below a shimmer, and swirl the pan continuously. If it still will not bind, lift out the fish and whip the warm oil and juices with a fine strainer until the sauce comes together.
What is the difference between bacalao al pil pil and bacalao al ajoarriero?
Pil pil is the coastal Biscayan preparation: whole skin-on loins poached in olive oil, with a sauce emulsified from the fish’s own gelatin, and almost nothing else in the pan. Ajoarriero is the inland preparation of Navarra and Aragón: the cod is shredded and stewed with peppers, tomato, garlic, and potato. Pil pil showcases the loin; ajoarriero stretches the fish. Pamplona’s own tradition is ajoarriero.
Is bacalao al pil pil Spanish or Basque?
It is Basque, specifically Biscayan, with Bilbao as its home city, and it spread from there to menus across Spain. In Euskara it is called bakailaoa pil-pilean. The salt cod itself was never local: it came through Bilbao’s port from northern Atlantic suppliers and later from Spanish fleets working the Newfoundland banks, which is exactly why a city on the Bay of Biscay built its signature dish on a preserved ocean fish.
Every article on the Encierro blog is authored or reviewed by active bull runners with direct experience in Pamplona.