In a large saucepan, heat the oil. Add minced onion and sauté for 6-8 minutes, stirring from time to time.
Add crushed garlic cloves and sauté for about 2 minutes or until the garlic releases its aroma.
Add 2 cups of pureed tomatoes, salt, pepper and calamari rings. Simmer covered on medium-low for 20 minutes. After 20 minutes, stir in olives and chopped parsley and simmer for a further 30 minutes or until the calamari is soft.
Enjoy as an appetizer or main dish!