While the mushrooms are cooling, prepare the sauce. Mix in a bowl three tablespoons of olive oil and dark balsamic vinegar, add a couple of pinches of salt and pink pepper (ground in a mortar). Beat everything well with a fork.
I advise you to adjust the taste for yourself after mixing all the ingredients, taking into account the fact that the sauce is slightly brighter than in the finished dish.
I added 2 teaspoons of balsamic.