Peel and chop the onion and garlic cloves. Melt the butter in a saucepan. Sweat the onion and garlic in it until translucent.
Add tomato paste and stir well with flour in a saucepan and let sweat. Puree the tomatoes beforehand. Then add the vegetable stock, tomatoes and sugar.
Let the soup simmer. Finally add oregano and marjoram, bring to the boil again and serve.