Heat the oil in a large pan and gently cook the onions until translucent. Add the garlic, cook for one minute then stir in the chilli powder and the tomato paste.
Add half the tomatoes and blend to a puree with a hand blender.
Pour in the stock then add the vegetables and the rest of the tomatoes. Simmer gently for about 20 minutes or until all the vegetables are tender.
Season with salt and pepper and serve with boiled rice, garnishing with parsley.