For the bouillabaisse, heat the oil in a large pan, add the fennel, celery and carrot and fry for 6-8 minutes, or until softened but not coloured. Add the chilli and garlic and cook for two minutes until soft.
Add the spices and fry for two minutes until fragrant. Add the tomatoes, tomato purée, orange peel, white wine and fish bones. Bring to the boil and simmer for an hour.
Skim the deep red oil from the surface of the bouillabaisse with a spoon and reserve it for the rouille.
Strain the stock through a fine sieve, pressing down firmly to extract some of the vegetables. Return the strained stock to the pan and keep warm until ready to serve.
For the rouille, put the garlic and egg yolk into a food processor. Turn the motor on and gradually add the chilli oil in a slow, steady stream until the mixture resembles mayonnaise. Season with a pinch of cayenne pepper and salt, to taste.
For the croûtons, preheat a grill to medium-high. Combine the oil, chilli powder and cayenne and brush generously over the baguette slices. Warm under the grill for two minutes, or until crisp.
For the bouillabaisse, return the pan to the heat and bring to a simmer. Add the parsley, tarragon, prawns, fish and squid and cook gently for five minutes. Divide the cooked fish between four serving bowls and ladle the liquid over the top. Top each bowl with a chilli crouton and a spoonful of rouille.