Baking salmon in a thick layer of salt not only looks incredible, but you’ll end up with the most perfectly cooked fish.
Preheat the oven to 180°C/350°F/gas 4. Wash the salmon well both inside and out, then pat dry with kitchen paper (leaving the scales on helps to keep in the moisture as it cooks). Finely slice 1 lemon and the fennel into rounds and stuff into the salmon cavity with the parsley, marjoram and chives.
Combine the rock salt, eggs and 250ml of water in a large bowl, then evenly spread one-third of the salt over a large baking tray (roughly 35cm x 45cm), making a slight hollow in the middle to hold the salmon snugly. Lay the salmon diagonally into the tray, then spoon over the remaining salt mixture, heaping it around and onto the salmon so that it’s evenly covered – you should have a layer of salt, roughly 2cm thick, all over the salmon. Place the tray in the hot oven for around 40 minutes, or until cooked through. To test if the salmon is ready, push a skewer through the salt into the thickest part of the fish – if it comes out warm after 5 seconds, it’s done.
Meanwhile, make the basil mayo. Place the egg yolk and mustard into a bowl, then gradually add the extra virgin olive oil, whisking as you go until silky smooth. Bash the basil leaves in a pestle and mortar, then muddle in a drizzle of extra virgin olive oil until you have a smooth paste. Push the paste through a fine sieve into the mayo, then stir to combine and have a taste, adding a squeeze of lemon juice or a splash of vinegar if needed, then set aside.
To make the salsa, finely chop the chilli and mint leaves, then place into a bowl with 1½ tablespoons of extra virgin olive oil and 1 teaspoon of vinegar. Season to taste with salt and pepper, then set aside.
Once cooked, remove the salmon from the oven and allow to cool for around 20 minutes, then with the tip of a knife, carefully slice into the salt, cutting all the way along the salmon spine, being careful not to slice into the fish at this point. Gently lift the salt casing off the salmon, then spoon away and discard the remaining salt, brushing away any excess from the top of the salmon.
Transfer the fish to a large platter, then score the skin along the spine, across the tail and under the gill and peel back the skin. Divide up the salmon and serve with the basil mayo, chilli salsa and lemon wedges for squeezing over.