1. Preheat oven to 180°C. Place the tomatoes, cut side up, and the capsicums on a large lined baking tray.
2. Drizzle with 1/3 cup olive oil and roast for 30 minutes or until soft. Remove the skin, roughly chop and set aside reserving any cooking liquids.
3. Heat the remaining oil in a large saucepan and sauté the onion until soft. Add the garlic and tomato paste and cook to 1 minute before adding the tomatoes, capsicums, remaining ingredients and reserved cooking liquid.
4. Simmer for 20 minutes. Cool slightly and puree with a stick blender, seasoning to taste.