Cook macaroni according to package directions until al dente, then strain.
For the lemon and sour cream sauce, first soak the dried porcini mushrooms in a little water.
Peel and chop the onion and sauté in a pan in a little olive oil until translucent. Peel the garlic and add it.
Cut the lemon-cured mushrooms into strips, add them and sauté well. Add the soaked porcini mushrooms together with the soaking water. Add some lemon zest and sauté well. Add a little more water if necessary. Season with salt and pepper, refine with crème fraîche.
Serve the macaroni with the sauce.