Smoked Mackerel Paté

Okay, so it’s cheating to use a recipe from the Guardian’s ‘Hot to cook…’ series, since they’ve already scientifically identified the perfect ingredients and method (!), but in this case there’s a slight tweak, as who can buy fresh horseradish in the UK? Even Waitrose staff insist ‘it’s the same as red radish’. Ahem. I should go to an ethnic food store, who will no doubt have loads of the stuff. But in this case, I substitute horseradish sauce.