Chop the carrots into coin-sized chunks, then chop the onion and bacon before frying them all off in a large pan with the butter (let these ingredients brown & caramelise slightly, as this is where the flavour comes from).
Add the tomatoes and the chilli/paprika (if using), then simmer for about 5 minutes.
Next add the flour, the tomato ketchup and the stock, then bring to the boil.
Simmer for 30 minutes until the vegetables are tender.
Place the soup in a blender and blend until smooth.
Then pass through a sieve into a clean pan using the back of a metal spoon to push it through.
Warm the soup through on a low heat.
While the soup is warming, in a small pan, heat the balsamic vinegar and sugar together until the sugar has dissolved.
Add the balsamic mix to your finished soup to taste.
Serve with fresh crusty bread and a swirl of single cream.