Finely chop the onion and sauté in olive oil, add the can of tomatoes and pour the vegetable stock over it, bring to the boil briefly. Put the kritharaki in the hot liquid, reduce the temperature and let it swell over a low heat for about 15 minutes. Keep stirring so that the rice noodles don`t stick. If necessary, pour in a little liquid again and again. If necessary, add a little olive oil at the end. Goes well with grilled Greek meat dishes such as souvlaki, bifteki or just as a vegetarian dish.