For the gravadlax, place the salt, sugar, vanilla seeds and pods into food processor and blend for 30 seconds.
Line a large, shallow, rectangular dish, with cling film. Sprinkle a third of the curing mixture over the base, then add the fish, skin-side down and cover with another third of the mixture, then top with the second piece of salmon, skin-side up. Spread the remaining curing mixture on top of the fillet and wrap in cling film. Leave to chill in the fridge for eight hours.
Rinse off the curing salt from the fish pat and dry with kitchen paper. Spread the mustard over the flesh side of the salmon, then sprinkle the dill over the top. Roll very tightly with clingfilm again and leave to chill in the fridge for a further six hours.
Carve thin slices from the salmon at a 45 degree angle.
For the deep-fried egg, bring a large saucepan of water to the boil, add the vinegar and a pinch of salt. Boil four of the eggs for five minutes. Remove the eggs from the saucepan using a slotted spoon, and leave to chill in a bowl of iced water.
Crack the remaining egg into a bowl - whisk and add a pinch of salt and freshly ground black pepper.
Peel the boiled eggs. Prepare a shallow plate of flour and a separate plate of breadcrumbs. Dredge the boiled eggs in the flour, then dip into the egg and roll in the breadcrumbs. Set aside on a tray in the fridge until needed.
Heat the oil in a deep-fat fryer to 180C/350F. Alternatively, pour the oil into a deep, heavy-based pan to a depth of 2cm/¾in and bring to the same temperature on the hob, checking with a sugar thermometer. (CAUTION: hot oil can be dangerous. Do not leave unattended.)
Fry the eggs until golden-brown. Remove with a slotted spoon, drain on kitchen paper and season with salt.
For the avocado salad, whisk the vinegar, honey, lemon juice and olive oil together in a bowl until well combined.
Mix the remaining ingredients in a bowl and drizzle over the dressing. Lightly toss to coat the salad ingredients with the dressing.
Lay slices of gravadlax onto a plate. Add a serving of salad alongside and place a deep-fried egg on top.