1. Preheat the oven to 180°C/350°F/Gas Mark 4.
2. Remove the stalks and seeds from the peppers and chop into small chunks.
3. Peel the onion and chop into chunks.
4. Place the peppers, onion, garlic and tomatoes on a large baking tray, drizzle with the oil and roast in the oven for 15 minutes.
5. Prepare the stock by dissolving the stock cube in 1 pint (570ml) of boiling water.
6. Remove the vegetables from the oven and empty into a large saucepan, add the stock, cracked black pepper, bring to the boil and then simmer for 10 minutes.
7. Remove from the heat and, using a blender (hand or jug), blend the soup until smooth.
8. Pour into a bowl and enjoy.