1. Cut the aubergine in half and score the flesh side in a criss-cross fashion, brush with oil and place under a hot grill until the flesh colours and softens.
2. Scoop out the flesh and chop up, then mis with the ricotta and shredded basil, season with salt and pepper.
3. Cut the tomatoes into quarters and cook in olive oil in a pan, meanwhile lay the mackerel fillets on a greased tray, season and brush with oil. Place under a hot grill and cook until the skin starts to crispen up, then turn and complete cooking on flesh side.
4. To serve, toast the bread and then spread on the aubergine mixture, top with the tomatoes and then the mackerel.