Slow-cooker caponata

• 1 tbsp oil
• 2 large aubergines, chopped into small pieces
• 2 sticks of celery, finely sliced
• 5 large vine tomatoes, roughly chopped
• 1 red onion, finely sliced
• 2 tbsp sundried tomato paste
• 3 tbsp red wine vinegar
• 1 tbsp brown sugar
• 1 tbsp capers
• 75g raisins

To serve

• 50g green olives
• 25g pine nuts, toasted
• 1 small handful fresh basil leaves
• ½ loaf Taste the Difference sourdough, sliced and griddled