Preheat the oven to 200°C fan / 220°C conventional / 425°F.
Chop the 6 large tomatoes in half and cut the red onion, red pepper and carrot into large pieces.
Add the large tomatoes, plum tomatoes, red pepper, red chillies and red onion to a large baking dish.
Slice the top off the head of garlic to expose the cloves and place it in the dish.
Drizzle everything generously with extra virgin olive oil and season with herby sea salt.
Roast for 45–50 minutes, or until the vegetables are soft, the tomatoes have released their juices and the edges are beginning to caramelise. Check towards the end, as cooking times can vary depending on the size and ripeness of the tomatoes.