Poach your fish for about 5 mins,I usually do this in the microwave adding bayleaves and a few peppercorns for flavour. Remove fish and leave to cool before flaking. Mix with 450g of mashed spud and add herbs of your choice,parsley or dill work well. Form into patties,then dust with flour and dip in one beaten egg.Roll in breadcrumbs and set aside to chill for about an hour. Gently fry until golden and cooked through. HTH
The simplest ones I know are from Nigel Slater's Kitchen Diaries (coincidentally one of the May MN Cookbook club books!)
These don't have any potato in them, but I can imagine if you wanted to make them more substantial you would add a couple of boiled and mashed up potatoes and then coat the cakes in breadcrumbs, while upping the quantities of dill, mustard and lemon juice.
500g salmon, skinned and finely chopped a large egg white a small bunch of dill, finely chopped 1 Tbsp flour 1 tsp grain mustard juice of half a lemon
Mix everything together in a bowl, mush together with a generous grinding of salt and pepper. Squash spoonfuls of the mixture together to make balls and flatten with your hands, set aside. Fry in olive or groundnut oil, 3-4 mins a side. They should be lightly cooked within and golden and crisp on the outside.
Serve with wedges of lemon, and a tub of yoghurt into which you stir chopped fresh dill, a spoonful of grain mustard, and some black pepper.