Clean the leek, cut in half lengthways, wash and cut into thin rings.
Melt the butter in a saucepan and fry the minced meat in it. Then add the leek and let it simmer over a low heat for a short time. Stirring occasionally.
In the meantime, wash the tomatoes and cut out the stems. Peel the tomatoes if necessary, then quarter and puree with the cutting stick. Add the tomato puree to the minced meat, then pour in 1/8 l of water. Season the stew with the vegetable stock, rosemary and oregano and refine with the cream. Cover and simmer over a mild heat for 15-18 minutes.