Mix 2 more tbsp horseradish with 2 tbsp creme fraiche, 2 tbsp cream, 1 tsp mustard and some pepper and salt.
Fry pp a fillet of mackerel in a lightly oiled pan , skin side down till the skin is nicely brown and crispy. Turn off the heat and turn the fish, It will be done in a minute and a half.
Serve as shown with watercress. I had some left over oyster mushrooms but that's not necessary.
(Inspiration: Dominic Chapman)