1. For the confit, set the oven to 180C/gas 4. Slice the aubergine and place on a roasting tray with the olive oil, shallot and garlic, and roast for 30 minutes. Remove and leave to cool in the roasting tray.
2. Bring a large pan of water to the boil and cook the fennel for 3 minutes, and then drain.
3. Heat 3-4 tbsp olive oil in a pan, add the chorizo, fennel, tomatoes and aubergine and season well.
4. Add the garlic and cook slowly for about 2 minutes and to cook the chorizo. Add the chopped basil and season again if nexessary.
5. While this is cooking, heat the remaining olive oil in a non-stick frying pan and season the bass fillets on each side. Add the butter and warm it until it is nutty brown. Add the bass fillets skin side down and cook quickly for about 2 minutes. When the skin is golden brown and crispy, turn over and remove the fish from the heat.
6. Arrange the confit in the middle of the dish and place the sea bass on top. Garnish with sprigs of fresh chervil and serve.