Heat the olive oil in a high-sided frying pan over a high heat, add the onion and aubergine with a big pinch of salt and fry until golden and softened, around 10 mins. Crush in the garlic with the oregano and cook for 1 min max, then tip in the capers and tomatoes. Half fill the empty can with water and add to the pan, bring to the boil then turn the heat down to a simmer until the sauce has thickened and the veg softened.
Toast the bread, then drizzle with a little more olive oil. Squash the cherry tomatoes a bit with the back of a spoon, then stir in half the basil and season the caponata, adding lemon juice, salt and black pepper to taste. Tip into bowls, top with the remaining basil and serve.