Mix together salt and the citrus zest and cover the redfish fillet in the cure.
Wrap the fillets loosely with cling film and place on a try in the fridge for a few hours.
To make the horseradish yoghurt, mix the yoghurt, horseradish cream and lemon juice together and refrigerate until required.
Remove fish from fridge, slice thinly.
Nathan Outlaw has kindly shared his recipe with Fishbox.
Outlaw has seafood restaurants in Cornwall and London, 'Restaurant Nathan Outlaw' in Port Isaac is his two Michelin-starred establishment.
Visit www.outlaw.co.uk to discover more about his restaurants, recipes and cookbooks.