Heat 1 tbsp oil in a heavy-based frying pan. Fry the aubergine in batches until golden brown and tender. Drain on kitchen paper, sprinkle with salt and set aside.
Wipe out the frying pan and add 1 tbsp oil. Heat over a medium-low heat, add onion and celery and cook for 8 mins. Add passata and cook for another 5 mins, stir in the capers and olives. Add sugar (if using) and vinegar, stir and cook for 5 mins. Turn off the heat, add the aubergines and gently mix together.
Serve in a bowl topped with fresh basil leaves and toasted pine nuts.
Recipe by appetite magazine at https://www.appetitemag.co.uk/celery-caponata/