Soused mackerel with crème fraîche & capers
James Martin's version of this authentic Scandinavian dish of 24 hour-marinated fish
Put potatoes in a pan of salted water, bring to the boil, then simmer for 12 mins until cooked through. Drain and cool.
Whisk buttermilk, light mayonnaise, mustard, vinegar and caster sugar with seasoning. Once spuds are cool, toss with the buttermilk dressing, radishes and poppy seeds. Sprinkle over cress to serve.