Chop the mushrooms in two and coarsely chop the garlic.
Start with frying the mushrooms, garlic and thyme for a couple of minutes. Season with salt and pepper. Mix in the onion and fry for another couple of minutes. Pour over the balsamic vinegar and remove from heat.
Sprinkle with the dill and parmesan cheese and give it a couple of twists of pepper mill. Place on a plate and serve.