For the sea bass, cut slashes into the skin side of the sea bass then season the other side with salt.
Heat a frying pan until hot, then add a little of the oil and some of the butter. Place the sea bass, skin side down, into the pan and cook for two minutes then turn over, cook for another two minutes then remove from the fish the pan.
For the mussel soup, heat a saucepan until hot, add some more of the butter and oil, the onion, garlic and star anise and cook gently for one minute.
Add the mussels and white wine and cover with a lid. Cook for 2-3 minutes or until the mussels have opened then remove the mussels with a slotted spoon and set them aside.
Add the fish stock to the pan and cook until reduced by one third then place the mixture in a food processor. Take care not to overfill the food processor, hot liquid could spurt out the top.Try filling up to a third, and test to see how far the liquid goes up the sides.
Remove the mussels from their shells and add blend two thirds of them in the food processor with the reduced stock. Blend the mixture to a fine purée then return it to the pan and add the cream.
Heat gently until it is warmed through and thick enough to coat the back of a spoon. Add the reserved mussels to the pan then season with salt and freshly ground black pepper.
For the courgettes, heat a clean frying pan until hot, add the remaining butter and oil and stir-fry the courgette ribbons carefully, taking care not to break them up. Season with salt and freshly ground black pepper.
To serve, pile the courgette ribbons into the centre of four soup plates. Top with the sea bass then spoon the soup around the edge.