- Place the haddock in a pan and cover with the milk. Simmer gently for about 10 minutes. Remove the fish, peel off the skin while still warm, and carefully flake the flesh into a bowl.
- Halve the cucumber lengthways, scoop out the seeds and cut into small cubes. Add this to the haddock, along with the diced pepper and shallot.
- In a small saucepan, boil the potatoes for 20 minutes or until tender. Drain and set aside a few minutes. Slice the potatoes and stir into the haddock mixture, along with the parsley. Bind everything together with the mayonnaise.
- Put the sour cream in a small bowl and stir in the horseradish sauce. Season with salt, cayenne pepper and lemon juice. You can mix in a spoonful of the poaching milk if you desire.
- Mix the tomato dice with the vinaigrette. Add the avocado and mix so they are well covered.
- Place the avocado and tomatoes on the plate, spoon over some of the haddock mixture and top with the horseradish cream. Finish it with some chervil.
- Serve immediately garnished with some chives.