Encebollado de rape: monkfish with onion

Ingredients

• 4 sections monkfish tail, each section 3–4 cm thick, trimmed of membrane
• 8–12 sweet onions, very finely sliced; Cebolla Dulce del País Vasco preferred, or the mildest yellow onion available
• 150 ml extra-virgin olive oil
• 150 ml dry white wine, white Rioja or Txakoli
• 1 small pinch saffron, crumbled into the wine
• fine sea salt

Method

1. 1
   Pour the olive oil into a wide, heavy-based pan — one large enough to hold the fish sections in a single layer later. Add all the sliced onions and a pinch of salt. Set the heat to the absolute lowest possible flame. The onions must not colour at the edges or sizzle aggressively; they should only soften and weep. Cook, uncovered, for 60–80 minutes, stirring occasionally, until the onions are completely soft, translucent, and sweet, with no residual sharpness. The mass will have reduced to roughly one-fifth of its raw volume.
2. 2
   Crumble the saffron into the white wine. Pour the wine over the softened onion and raise the heat very slightly. Cook for a further 10 minutes, stirring, until the wine has largely reduced into the onion base and the pan smells of sweet, wine-scented onion with no raw alcohol.
3. 3
   Season the monkfish sections lightly with salt and lay them on top of the onion in a single layer. Cover the pan and cook on low heat for 15 minutes. The fish is done when it is just opaque throughout and yields to gentle pressure with a fingertip — it should feel firm but not resistant, with no translucency at the centre. Internal temperature: 60 °C.
4. 4
   Taste the onion sauce and correct for salt. Serve the fish sections directly from the pan with the onion spooned generously around and beneath each piece.