Put a pot with 2 liters of water and a tablespoon of coarse salt on the stove: when it starts to boil, add the previously rinsed barley and the potatoes cut into chunks. Leave to cook on a low heat for 45 minutes.

Clean the leek and cut it into slices. Peel and chop the celery, carrot and onion. Clean and cut the mushrooms.

Place another pot on the stove with the vegetable broth and bring to a gentle boil. Add the leek, onion, celery and carrot and cook for about 5 minutes. Add the mushrooms and cook for another 5 minutes.

Drain the barley and potatoes and pour them into the pot with the broth and vegetables, then continue cooking for another 5 minutes, taking care to mash the potatoes with a wooden spoon. Season with salt.

Sprinkle the soup with chopped parsley and pepper and arrange in individual bowls.

Complete with grated spicy aged Provolone Valpadana DOP and serve.