Heat olive oil in pan over medium heat. Add garlic, and saute for 20 seconds.
Add onion, and saute until translucent.
Add whole tomatoes, sugar and oregano. Break up tomatoes with spoon. Simmer for at least 40 minutes. Continue to break tomatoes with spoon as you stir occasionally.
Taste, add salt and pepper as needed. Add basil at the end if using, bring sauce back to boil, and remove from heat. Allow to cool slightly before spreading on pizza.
Makes enough for 2 pizzas.
Freezes very well for future use if desired.