Pork, Potato and Vegetable Gratin

Wipe the mushrooms clean with a damp cloth and slice. Peel the potatoes and cut into wedges. Cut the white and light green parts of the leek into rings and rinse well. Cut the meat into slices.

Peel and finely chop the onion. Heat 1 tablespoon butter in a pan and saute the onion until translucent. Add the vegetables and saute, stirring for about 3 minutes, season with salt and pepper.

Preheat the oven to 180°C (approximately 350°F). Grease a baking dish. Place the roast meat and the vegetable mixture into the baking dish and pour the broth over.

In a bowl, whisk together the eggs, creme fraiche, cream and mustard and half the cheese, season with salt and pepper. Pour over the casserole and sprinkle the remaining cheese on top.