Halve or quarter the mushrooms depending on their size, then fry them in a Teflon pan without adding any fat. As soon as the mushrooms turn brown and wrinkled, add the bacon. Fry briefly, remove from the plate.
Make a vinaigrette in a bowl with vinegar, oil, salt, sugar and pepper. Then add the lamb`s lettuce and the still lukewarm mushrooms and mix everything together.