Prepare the vegetable stock. Slice the onions finely and stew them in a pot with extra virgin olive oil and a little stock until they are soft.
Add the diced or sliced potatoes, the rosemary and hot stock and cook until tender. Blend with a hand blender, after removing the sprig of rosemary.
Cut the Parma Ham PDO into strips and sauté in a frying pan, drizzling Balsamic Vinegar of Modena PGI over it.
Serve the soup hot in individual ramekins sprinkled with a tablespoon of Parma Ham PDO and white pepper.
