Ingredients
For the poaching liquor
4 celery sticks
4 carrots
2 large onions
2 bay leaves
1 tsp black peppercorns
1 tsp coriander seeds
400ml/14fl oz dry white wine
200ml/7fl oz white wine vinegar
For the sewin
4 sewin (sea trout) fillets, each about 175g/6oz, skin on
400g/14oz live cockles in their shells, washed (discard any that don't close when gently tapped)
100g/4oz wood sorrel, to garnish
50ml/2fl oz extra virgin olive oil, to serve

Method
1. To make the poaching liquor, slice the celery and carrots on the diagonal, to the same thickness. Halve the onions, place the halves cut-side down and slice into semi-circles. Throw these vegetables into a wide lidded saucepan and add the remaining ingredients and 100ml/3½fl oz cold water. Bring to the boil and simmer for 30 minutes. Remove from the heat.
2. Add the sewin to the poaching liquor. Return the pan to a gentle heat and cook, uncovered, for 6-7 minutes. Do not allow the liquid to boil. Remove the fish and keep warm. Lift the vegetables out of the poaching liquor with a slotted spoon and keep warm.
3. Pour most of the poaching liquor out of the pan, leaving behind just enough to cover the bottom. Bring this to the boil and add the cockles. Cover with the lid and cook, shaking the pan from time to time, until the cockles open - this should take 2-3 minutes. Discard any that do not open. Drain the cockles and remove them from their shells, keeping some in the shell for the garnish.
4. To serve, place some soused vegetables onto each of four warm plates with the sewin on top, and scatter the cockles around. Garnish with the wood sorrel, a splash of olive oil and the cockles in their shells.