- Peel and finely chop the garlic and red onion. Trim and roughly chop the carrots, celery and zucchini. Then add the vegetables to a large bowl. Cut the ends off the leek and then cut it in half. Wash the leek under running water and slice into 1cm slices. Add to the bowl. Peel and dice the potato. Open the can of tomatoes and roughly chop them. Set aside.
- Heat 3 tablespoons of olive oil in a large saucepan over a medium heat. Add the garlic, red onion, carrots, celery, zucchini, leek, dried oregano and bay leaf. Cook slowly for about 15 minutes or until the vegetables have softened. Stir occasionally.
- Add the potato and the peeled tomatoes (chopped). Then pour in half a litre of water and stir well. Cover with a lid and bring slowly to a boil, then simmer for about 30 minutes or until the potato is cooked through.
- Break the spaghetti into pieces in a clean plastic bag or in a clean towel. Add the pasta into the pan and cook for a further 10 minutes or until the pasta is cooked. Check if it needs more water and add the remaining if necessary, season to taste with salt.
- Serve the soup with slices of toasted wholegrain bread and a drizzle of olive oil.