Clean the porcini mushrooms with the mushroom brush and rinse for a short time (!) And pat dry.
Cut the caps vertically and the stems horizontally into fine slices. Mix the vinaigrette with the mustard, vinegar, oil, pepper and salt. Cut the shallot very finely and add it to the vinaigrette. Finely chop the parsley. Arrange the porcini mushroom slices in a fan shape on a plate, spoon the vinaigrette over it and let it steep for 10 minutes.
Sprinkle with the chopped parsley.
It goes well with a brioche, baguette or just toast.
Of course, a light white wine (preferably Chardonnay) should not be missing!