Cut all the vegetables into roughly ½ inch pieces and set aside - keep the potato and swede separate.
Heat the oil in a large heavy-bottomed pot and add the onion, carrots, celery and courgette/zucchini.
Cook the vegetables, stirring occasionally, for 5-10 minutes until they start to sweat and soften.
Add the garlic, thyme, bay leaves and ½a teaspoon each of salt and pepper and stir. Cook for 2-3 minutes until the garlic becomes fragrant.
Add the chopped potato and swede then pour over the chopped tomatoes and stock.
Stir well, then bring to a boil.
Once boiling, turn the heat down and let the soup simmer until the potatoes are soft - about 20 minutes. You should be able to easily pierce them through with a fork.
Remove from the heat and carefully discard the bay leaves from the pot - they should easily rise to the top of the pot during cooking but you may need to give it a stir.
Using an immersion/stick blender, puree the soup until smooth. You can also use a stand blender to do this in batches.*
Season to taste and serve the soup warm with some bread or crackers for dipping. Garnish with some fresh chopped chives or parsley.