Cut the tomatoes in half and place them on a large baking tray.
De-seed the peppers and cut them into 4 wedges. Put these on the tray, skin-side up. Cut the onion in half. Add the garlic cloves and onion to the tray.
Drizzle some olive oil on the top of the vegetables, sprinkle with the oregano and season with salt and pepper.
Bake for 30 minutes until the tomatoes are tender and the skin of the peppers are brown.
Transfer the tomatoes and the cooking juices to a saucepan. Pop the garlic and onion flesh out of their skin, discard the skin. Add the garlic and onion to the tomatoes.
Let the peppers cool in a bowl under cover, then remove the skin and add the flesh to the pan.
Pour in the stock and bring to a simmer.
Using a stick blender, whiz until you get a smooth soup. Add the herbs and season to your liking. Blitz again for a few seconds.
Serve warm with crusty bread.