Cod in aioli sauce

Preheat the oven to 180°C/gas mark 4

For the aioli sauce, bake the potato in the oven until cooked through

Meanwhile, start on the stock. Fill a large saucepan up with the 1.5 litres of mineral water and place the vegetable trimmings (fennel tops, carrot peel, celery peel) into the pan

Rinse the fish trimmings and bones under cold water and add to the pan with the herbs, black peppercorns, salt, halved onion, leek and 1 1/2 of the garlic heads, sliced open. Cover the pan and simmer on a very low heat

After 20 minutes, strain the stock into a clean pan and cook each vegetable one by one in the stock until tender. Set aside the vegetables once cooked, leaving the stock to simmer

To prepare the cod, slice the cod into four chunks. Sprinkle a tray with coarse salt and lay the fish on top, sprinkle with more salt to cover the fish. Place in the fridge for half an hour

Remove the potato from the oven and scoop out the flesh. Place the 1/2 a head of garlic in a pestle and mash with a mortar. Add the flesh of the potato, 2 tablespoons of the stock and the egg yolk. Continue to crush the mix with the mortar until smooth

Once smooth, start to incorporate the olive oil incrementally, like you would do for a mayonnaise. Season to taste and set aside

Rinse the salt from the cod and poach in the stock on a very gentle simmer. Add all of the vegetables into the broth to warm through after 5 minutes of cooking

Arrange the cod and vegetables between plates with hard boiled egg halves, drizzle with the aioli sauce and serve immediately