Method:
1 Preheat the oven to 200°C fan forced.
2 Heat oil in a frying pan over a medium heat add the butter and swirl to melt. Coat fish in flour and pan fry for 3-4 minutes on each side or until cooked through.
3 Place wine, mandarin rind and juice, onion and peppercorns in a saucepan, bring to the boil over high heat. Reduce to medium and simmer for 2 minutes or until reduced by half. Strain into a saucepan and discard solids. Place over medium heat, whisk in the chilled butter a little at a time until well combined, remove from heat and season to taste with salt and pepper.
4 Plate the fish and pour over the sauce to serve