Fry the minced meat with a little salt and pepper. Cut the leek into rings and add. Mix the broth in the measuring cup - I usually take 250 ml plus water as required (sense of proportion). Add mustard and ketchup and simmer for 20 minutes. Finally stir in the crème fraiche.
Cook the pasta as usual.
Now first arrange the pasta on plates, then add the minced meat mixture on top and serve immediately.