Cover with a lid and poach for 3 minutes or until just cooked. Set the haddock aside (reserving 2 tbsp of the milk), then remove the skin form the fish and fork the flesh into large flakes.
350g / 12oz smoked haddock fillet
450g / 1lb floury potatoes
150ml / ¼ pint milk
25g / 1oz butter
1 onion, finely chopped
140g / 5oz baby spinach
1 egg, beaten
Bread crumbs for coating
Vegetable oil for frying
For the mustard mayonnaise
175g / 6oz mayonnaise (see below)
2-3tsp grainy mustard
2 tbsp double cream
For the mayonnaise
300ml / ½ pint sunflower oil
1 tbsp white wine vinegar
1 tsp Dijon mustard
Salt and white pepper
Fry the onion in the butter over a low heat until soft. Once the potatoes are tender drain well and put through a ricer into the buttery onion mixture. Cook the spinach by placing in a colander and pouring over boiling water. Cool with cold water then squeeze out excess fluid and chop.
Mix the spinach with the onion mash, then carefully fold in the fish – try to keep the flakes large. Wet your hands and shape the mixture into 8 cakes, dust with seasoned flour. Chill the cakes for 30 minutes. Dip each cake in beaten egg, then breadcrumbs and fry in hot oil for 3-4 minutes on each side. Serve with mustard mayonnaise and a green vegetable.
To make the mayonnaise place the egg, vinegar, mustard and salt and pepper into a food processor. Process until well combined, then slowly add the oil through the feeder tube in a drizzle. The mayonnaise will get thicker with the more oil that’s added. Adjust seasoning if needed then store in the fridge for up to 5 days. To make mustard mayonnaise simply mix all the ingredients together.
To get ahead: The cakes can be assembled ready to cook and kept in the fridge for 2 days ahead. The mayonnaise can be kept for 2 days in the fridge.
To freeze: The cakes can be assembled ready to cook, then frozen for up to 1 month ahead. The cakes can be cooked from frozen by cooking for 5 minutes on each side. The mayonnaise cannot be frozen.