Cut the meat into strips. Clean and wash the carrots and leek. Cut carrots lengthwise in half and cut them diagonally into pieces. Cut leek into rings. Peel and chop onion. Heat the oil in a large pan and fry the meat in it thoroughly.
Add leek, carrots and onions, sauté briefly and season with salt and pepper. Deglaze with broth and simmer covered for about 10 minutes. In the meantime boil 1/2 litre of water and a teaspoon of salt for the puree.
Remove from heat, add milk and stir in the puree flakes briefly. After 1 minute stir again and keep warm. Wash parsley, dab dry and chop except for a little bit for garnishing. Pour cream to the shredded meat, bring to the boil and add the sauce thickener while stirring.
Bring to the boil again briefly and season to taste with salt and pepper. Arrange on plates with the mashed potatoes. Serve sprinkled with parsley and garnished.