Heat the oven to 200C (180C fan)/390F/gas 6.
Halve any larger tomatoes and keep the smaller ones whole.
Toss in a large roasting tin with three tablespoons of the olive oil, the garlic and a good scrunch of sea salt. Roast for 20 minutes.
Toss the chunks of sourdough in the remaining olive oil, spread out on a flat baking sheet and bake for 10 minutes or until golden brown.
Add the vinegar, olives, basil and half the bread to the baking tin with the roasted tomatoes to soak up all the juices.
Scrape into a serving dish and add the rest of the sourdough and mozzarella. Finish with extra basil and a drizzle of olive oil.
