Wash the morel mushrooms (or the substitute mushrooms) several times, then parboil them in salted water for 5-8 minutes, place on a sieve, and let cool.
Meanwhile, sauté the onion in lard, add the finely chopped mushrooms, season with salt and pepper, and braise for about 8-10 minutes, until the mushrooms release their liquid.
Add the chopped roasted veal and the parsley, mix well, then add the broth, and braise for a few more minutes, until the filling is thick but not too dry.
Stuff the cooled morels with most of the filling.
Arrange the stuffed mushrooms in rows in an oven-safe dish.
Thin the remaining filling with sour cream, and pour it over the mushrooms.
Bake in a preheated oven at 190°C for 20-25 minutes, until the top is lightly golden.
Serve warm.
Based on: Malatinszky Fanny szakácskönyve (a classic Hungarian cookbook), modernised. Calories and protein are estimated.