Fish Pot-au-Feu

Peel the prawns, reserving every shell and head. Pat prawn tails dry and refrigerate. Pin-bone and portion the salmon and halibut. Prepare all vegetables as listed. Separate parsley stems from leaves; roughly chop parsley leaves and set aside with chervil.

Heat a large heavy-based saucepan or stockpot over high heat. Add 1 tbsp olive oil and, once shimmering, add the reserved prawn shells and heads. Sear without stirring for 3 minutes until deeply pink and toasted, pressing the shells against the pan to extract maximum flavour.

Add the halved onion (cut-side down), halved garlic head, tomato halves, fennel seeds, peppercorns, parsley stems, thyme, and bay leaves to the pot. Cook over high heat for 2 minutes, stirring once, until the aromatics are slightly charred.

Pour in the white wine and scrape up any caramelised bits from the base of the pan. Cook at a vigorous simmer for 3 minutes until the wine is reduced by half.

Add 1.5 litres of cold water and the first pinch of saffron. Bring to a boil, then reduce to a gentle simmer and cook uncovered for 25 minutes until the broth is richly golden and fragrant.

Strain the broth through a fine-mesh sieve into a clean wide saucepan or deep sauté pan, pressing firmly on the solids to extract every drop. Discard the solids. Season the broth with 1 tsp salt and taste for balance.

While the broth simmers, make the rouille. Using a pestle and mortar, pound the garlic cloves and a pinch of salt to a smooth paste. Transfer to a medium bowl and whisk in the egg yolks, Dijon mustard, and saffron-bloomed water until combined. Slowly drizzle in both oils, whisking constantly, to form a thick emulsion. Stir in lemon juice and adjust salt. Refrigerate until needed — since this sauce stays raw throughout, use pasteurised egg yolks if serving anyone pregnant, elderly, very young or immunocompromised.

Bring the strained broth to a steady simmer over medium heat. Add the potato rounds and cook for 10 minutes until barely tender when pierced with a knife tip.

Add the carrot batons and celery and cook for 5 minutes until beginning to soften.

Add the leek lengths and fennel wedges and cook for 4 minutes until all vegetables are just tender but still holding their shape.

Add the butter and remaining 1 tbsp olive oil to the simmering broth, then nestle in the clams and mussels. Cover and cook for 3 minutes until the shells have opened — discard any that remain firmly shut.

Reduce the heat to the lowest possible setting. Gently lower the salmon, halibut, and peeled prawns into the broth. Poach uncovered for 5 minutes, or until the fish reaches an internal temperature of 63°C when checked with a meat thermometer and the prawns are opaque and pink throughout.

To serve, distribute the vegetables among four warmed wide bowls. Lay the fish portions, prawns, and opened shellfish on top. Ladle the hot saffron broth generously over everything. Scatter with chopped parsley leaves, torn chervil, and the reserved fennel fronds. Serve immediately with toasted baguette and the rouille on the side for spreading.