Heat the oil in a large saucepan and fry the onion for 5 minutes. Add the tomatoes, cover and cook for a further 5 minutes. Stir in the stock, bring to the boil. Roughly tear up the bread and add to the soup. Simmer for 5 minutes.
Add the basil and purée with a hand blender or food processor. Season to taste.
Try adding some smoked back bacon with the onion for extra flavour. Ideal served chilled in summer.
Freezing and defrosting guidelines
Make the soup, then leave to cool at room temperature. Freeze (without garnishes or toppings) in a rigid container, leaving a bit of space for expansion, for up to 1-3 months. Reheat either from frozen or defrost in the fridge overnight. Once piping hot, add toppings or garnishes and serve.