Drain tomatoes in a strainer set over a bowl. Set juice aside. In a blender or food processor fitted with a metal blade, mix tomatoes until smooth.
In a large pan, heat oil over a medium-low heat. Add garlic and onion, cook, stirring frequently, for 2 minutes. Stir in pureed tomato. Reduce heat to low, cover and simmer for 10 minutes, stirring occasionally.
Stir in reserved tomato juice, stock, carrot, celery, pasta, parsley and pepper. Simmer until vegetables are tender, about 25-30 minutes. Ladle soup into serving blows. Garnish with parsley. Serve.