Smoked haddock and watercress fishcakes with gribiche mayonnaise

Method

1. Combine the ingredients for the gribiche mayonnaise in a small bowl, cover and chill until needed.
2. Peel the potatoes and cut them into large chunks. Put in a pan of well salted cold water (1 tsp salt per 600ml water). Bring to the boil, then cook for 20 minutes until tender.
3. Meanwhile, bring another wide, shallow pan of water to the boil, add both types of haddock fillet and simmer for 8 minutes. Lift the fish onto a plate and, when cool enough to handle, drain away any excess water from the plate, then break fish into flakes, discarding the skin and any bones.
4. Break off the larger stalks from the watercress (use for soup) and roughly chop the leaves. Melt the butter in a large pan over a medium-high heat. Add the watercress and stir for about 1 minute until wilted. Lightly stir into the potatoes with the flaked fish and plenty of seasoning to taste. Leave the mixture to cool.
5. Divide the mixture and, with lightly floured hands, shape into 8 even-size fishcakes. Put on a tray lined with cling film, cover and chill for at least 1 hour to firm up.
6. Heat the oil for deep-frying as in the master recipe (see tip). Put the 50g flour, beaten egg and breadcrumbs in 3 separate shallow bowls. Coat the fishcakes one at a time in flour, beaten egg, then breadcrumbs. Deep-fry, 2 at a time, for about 7 minutes, turning halfway through, until crisp and golden. Serve with the gribiche mayonnaise.