Put a large stock pot over a medium flame and heat the oil. Add the passata and salt. Bring to a boil and cook for about 5 minutes while stirring with a wooden spoon.
Add the water and bring to a boil. Taste for seasoning and add more salt as desired.
Drop in the pastina and cook until al dente, about 6-7 minutes. Ladle info bowls and serve with crusty bread and a sprinkle of grated cheese.