Prepare the Dollaghan by de-boning the trout fillet, rinse under cold water and pat dry and leave to one side.
Mix the dry cure ingredients, together and rub onto the trout fillet, wrap tightly in cling film and leave to cure for up to two hours.
Add the brown crab to boiling salted water for 8-10 minutes or until cooked. Remove and refresh in cold water. Dissect the crab removing any crab meat and separating any waste.
To prepare the bouillabaisse, sweat off the chopped onion, fennel, leek, garlic and celery for 6-7 minutes. Add the brandy and sherry and reduce, add in the fish stock, crab shells and crab meat, bay leaf, star anise, and tomato paste and reduce for 2 hours.
Roast the tomatoes for 8-10 minutes, add to the bouillabaisse and reduce until a third of the liquid remains. Remove from the heat, purèe the mixture and pass through a fine sieve. When cool transfer into a plastic bottle and refrigerate until ready to serve.
To make the anchovy emulsion, beat the egg yolk with the white wine vinegar until slightly thickened. Pour in the rapeseed oil very slowly, continually whisking until an emulsion is formed.
Add the saffron, anchovies and smoked paprika and pulse in a blender until smooth. Pass through a fine sieve, transfer into a plastic bottle and chill.
Wash off the Dollaghan under cold water, and pat dry. Rub with a little oil, and sear with a blow torch fr 1-2 minutes to finish.
Portion the dollaghan. Present on a plate. Add some of the crab sauce, anchovy emulsion and herring roe then garnish with a sea purslane.