Heat olive oil in a heavy-bottomed soup pot

Add the onion and pancetta

If pancetta is unavailable, substitute lean salt pork or bacon blanched in boiling water to remove the smoked flavor

Cook over medium heat for a few minutes until the onion just begins to soften

Add the celery, carrots, and tomatoes, stir to coat with the oil, and gently saute for 5 minutes

Add the water, half the cubed potatoes, pepper, and the rosemary

Bring the soup to a boil then simmer for about 45 minutes, stirring occasionally

The potatoes should be very soft so that the starch thickens the soup and creates a creamy texture that blends the flavors of the rosemary and tomato

Add the rest of the potatoes and salt, and cook until the potatoes are just about tender, adding more water if necessary

Then add fresh pasta and cook until al dente.