Put the onion, garlic, carrot and cilantro stalks into a large pot with the olive oil. Cover and cook gently for 10 mins, stirring regularly to prevent colouring.
Meanwhile, drop the tomatoes into boiling water for a minute or two. Take them out, run them under the cold tap, then pinch the skins off, discard, and roughly chop the flesh. Add to the pan with broth and pasta sauce. Simmer for another 20 mins with the lid on.
Whiz your soup in a blender, then pour it back in the pan and season well. Serve with a sprinkling of cilantroleaves and a few chopped chili peppers if you dare!