Optional: Wash the aubergines, cut the stalk and base and cut the flesh into 2.5cm cubes. Place in a colander and add 3tbspn sea salt. Toss to cover all the cubes and leave for an hour to allow the bitter juices to seep out. Wash and press dry. Salting the aubergine prevents the aubergine from soaking in lots of oil while frying.
Heat 2tbspn of the oil in a large, thick bottomed saucepan, add the onion and celery and gently fry until soft. Add the garlic and cook for 5min, then add the tomatoes and 1tbspn salt. Simmer over a medium heat for about 25min.
In a separate large non stick pan, heat 4tbspn of olive oil. When very hot, place one layer of aubergines in to brown. Use tongs to turn cubes over so that they brown on all sides. Remove and drain on kitchen paper. Repeat with the remaining aubergines cubes until all fried. Sprinkle the aubergine with the vinegar and season with salt and pepper.
Season the tomato sauce, then stir in the aubergines, olives, capers and the parsley.