Directions

1. To make the base, heat the oil in large saucepan and sweat the onion, garlic, star anise, carrot, fennel, celery, bay leaves and thyme for 15–20 minutes until soft and starting to colour. Add the fish, shells and bones to the pan and continue to cook for another 10 minutes or so. Add the tomato purée, saffron, vermouth and tomatoes. Cook to a paste then barely cover with water and simmer very gently for 30 minutes.
2. After this time, blitz briefly with a hand blender. Drain in a colander and push through as much liquid as possible. Discard the bones and shells, transfer the base back to a saucepan and add the tarragon. Boil until reduced to around half the volume, skimming off any fat as it cooks. Taste and season with salt and pepper.
3. To make the fish, place a dry saucepan over a high heat. Discard any mussels with broken shells and any that refuse to close when tapped. Add the mussels, wine, bay leaf and garlic, immediately cover with the lid and shake the pan from time to time. After 2–3 minutes, check all the mussels have opened. Discard any mussels that remain closed and remove from the heat. Tip into a sieve or colander, collecting any cooking liquor in a bowl underneath.
4. Leave to cool slightly before picking the meat from the shells and set aside. Strain the cooking liquor through a fine mesh sieve or chinois and tip into the reduced base. Heat the oil in a frying pan and fry the fish on one side (depending on the thickness) until cooked through. Keep warm with the mussels.
5. To make the rouille, grind some salt with the garlic, chilli, smoked paprika, red pepper and saffron with a pestle and mortar to make a paste. Set aside. Put the egg yolks and mustard in a bowl and slowly whisk in the oils by hand until incorporated and thick. Add the red pepper paste, vinegar and lemon juice and season with salt. Set aside.
6. To make the croûtons, warm the olive oil in a frying pan with the smashed garlic clove to infuse. Add the croûtons and toast on both sides until golden brown. Add the thyme and butter to the pan and baste. Transfer to kitchen paper to drain. Keep warm.
7. To serve, put the cooked fish and mussels in the bottom of a large serving bowl. Ladle the fish base over the top and serve the rouille and Gruyère in small serving dishes alongside. Serve the croûtons on a separate side plate.