Basque Country, Spain
The Basque onion-fish preparation — thick monkfish tail sections slow-cooked in an extraordinary quantity of onions, olive oil, and white wine until the onion has completely dissolved into a silky, barely-there sauce and the monkfish is just cooked through. The technique is the same as the French confit d'oignon applied to a fish preparation: the onion is cooked on very low heat for an extended period until it loses all its sharpness and becomes sweet, slightly caramelised, and almost transparent. This is not a quick preparation. The onions require 60-80 minutes of slow cooking before the fish is added. But the result — monkfish of remarkable delicacy set against a sweet onion sauce with no cream, no butter, no thickener beyond the onion's natural sugars — is one of the most elegant preparations in the Basque repertoire.
Slice onions very thin — they must dissolve, not remain as pieces. Cook in generous olive oil on the absolute lowest possible heat for 60-80 minutes until completely soft, translucent, and sweet. Add white wine and cook 10 more minutes. The monkfish sections (3-4cm thick) go in on top of the onion for the final 15 minutes, covered. The fish should be just cooked through — internal temperature 60°C.
The onion quantity seems excessive when raw (typically 2-3 onions per portion) — it reduces dramatically during the long cook. The Basque tradition uses local onions (Cebolla Dulce del País Vasco) which are milder and sweeter than standard yellow onions. A small pinch of saffron added to the wine reinforces the colour and adds aromatic complexity. Pair with white Rioja or Txakoli.
Rushing the onion — pale, harsh onions produce a harsh sauce. Adding the fish before the onion is completely soft. Cooking the fish too long — monkfish becomes rubbery quickly. Adding cream — the dish is specifically about the clean sweetness of the dissolved onion.
The Basque Book by Alexandra Raij