Clean and wash the leek and cut each stick into 2-3 equal pieces. Blanch in boiling salted water for about 10 minutes. Heat the oil in a large frying pan. Fry the ground pork in it until crumbly.
Cut the tomatoes in the tin smaller, add to the mince and bring to the boil. Drain the leek, drain well and add to the minced meat sauce. If necessary, season with salt and pepper and let it braise for 10 minutes.
For the puree, boil 1/2 litre of water and a level teaspoon of salt. Remove the pot from the heat and add the milk. Stir in the puree flakes. Stir again after 1 minute. Wash parsley, dab dry and chop.
Serve the leek with minced sauce and mashed potatoes. Sprinkle with parsley and garnish.