1 reduced salt vegetable stock cube, made up to 900ml
Preheat the oven to 220°C, fan 200°C, gas 7. In a large saucepan over medium heat, combine the onion, carrot, celery, sweet potato, red pepper, garlic, and tinned tomatoes. Bring to a boil, then reduce to a low heat for 5 minutes.
Place the flatbread triangles on a baking tray in the meantime. Drizzle 1 tbsp oil over the top and bake for 10 minutes, or until brown.
Fill the pot halfway with stock, stir well, cover, and simmer for 25 minutes, or until all the veggies are soft.
Using a hand blender or a food processor, blitz until smooth. Serve with a sprinkle of olive oil and flatbread croutons.