Cut the leek into pieces 8-10 cm long. Remove the middle layers, taking into account the desired thickness of the tube.
For the filling, season the minced meat with salt, pepper, coriander and thyme. Finely chop part of the leek from the middle layers and the mushrooms.
Mix the filling well and fill the tubes with a teaspoon. Lightly fry the tubes in a frying pan on all sides, sprinkle with grated hard cheese on top and bring to readiness in the oven (about 30 minutes at 180 C).