Red onion is cooked down until golden and tender along with firm swordfish before red wine vinegar and sugar are added, creating a sweet, sticky and slightly sour sauce that works well with the meaty fish.
- 1 large red onion
- 250ml red wine vinegar
- 200g caster sugar
- 3 tbsp. oil
- 4 swordfish steaks
- Salt and pepper
Thinly slice the red onion. Heat 1 tbsp. of the oil in a large heavy-bottomed frying pan. Add the onion and fry very gently over a low heat for 15-20 minutes until very browned and tender. Scoop the onion from the pan with a slotted spoon and set to one side.
Heat the rest of the oil in the frying pan and turn the heat up high. Season the swordfish on either side with salt and pepper and sear on either side for 1 minute. Remove from the pan.
Put the sugar and vinegar back into the pan. Stir and heat until the sugar dissolves into the vinegar. Add the onions, then turn the heat up and simmer until thickened and syrupy. Add the swordfish steaks, cover and simmer for 5-6 minutes or until the fish flakes easily and is no longer translucent in the middle.
Serve the fish with the onions and sauce spooned over the top.