Preheat oven to 220°C/200°C fan.
To a large, high-sided oven-proof skillet, add cauliflower, onions, celery, garlic, olives, raisins, capers, 2 tablespoons olive oil, 2 tablespoons white wine vinegar, salt + freshly ground pepper. Toss to coat.
Roast for 25 minutes until slightly charred.
Reduce oven to 200°C/180°C fan.
Add the tomatoes + mix. Roast for another 40 minutes until the sauce is thick + jammy.
Remove from oven + add 1 tbsp white wine vinegar, half the basil, salt + pepper. Toss to combine.
Finish with a drizzle of olive oil + the remaining basil. Serve alongside warm toasted sourdough for mopping.
