• 2 leeks, white part only, finely chopped, ½ leek reserved
• 1 onion, peeled, finely chopped
• 50 g (1¾ oz) butter
• 2½ tablespoons grapeseed oil
• 250 ml (9 fl oz/1 cup) milk
• 250 ml (9 fl oz/1 cup) cream
• ½ a sebago (all-purpose) potato, peeled, sliced
• 250 g (9 oz) salmon belly, skin and sinew removed
• 50 g (1¾ oz) grey salt
• 50 g (1¾ oz) sugar
• 1 litre (35 fl oz/4 cups) olive oil
• 4 quail eggs, soft-boiled
• 4 teaspoons salmon caviar
• 4 teaspoons beluga caviar

Preheat the oven to 260°C (500°F/Gas 9). Lay the reserved half leek on a foil-lined baking tray. Roast for 10–20 minutes or until blackened, dry, and crisp. Allow to cool. Break into fine shards. Leek ash will keep for up to 3 days in an airtight container at room temperature.

Put the chopped leek, onion, butter and grapeseed oil into a frying pan over low heat, and sweat until soft and translucent. Season with salt and pepper and reserve 8 tablespoons of the leek mixture for serving. Add the milk, cream and potato to the pan and cook for 15–20 minutes until the potato is soft. Purée the mixture in a blender until smooth, season with salt and pepper, then pass through a fine sieve. Put the mixture in an espuma gun with a double charge and set aside until ready to serve. Be careful not to fill the gun past three-quarters full.

Lightly cure the salmon in the grey salt and sugar for 30 minutes. Rinse gently and pat dry with paper towel, leaving it uncovered until ready to cook. Poach the salmon in the olive oil at 52°C (126°F) for 8–10 minutes. Remove from the oil and drain on paper towel.