1) Place extra-virgin olive oil in large sauce pot over medium high heat, add onions and reduce heat to medium.
2) Saute onions until golden brown then add tomato puree, cook for 1 minute. Turn heat back to high, add remaining ingredients with exception of salt and pepper. Bring to a boil, reduce heat to medium and simmer ingredients for 10 to 15 minutes.
3) Remove pot from heat, place into blender* and puree until smooth. Add salt and pepper. If the mixture is not smooth enough add a few teaspoons of water and puree until smooth.
* When blending hot liquids: Remove liquid from the heat and allow to cool for at least 5 minutes. Transfer liquid to a blender or food processor and fill it no more than halfway. If using a blender, release one corner of the lid. This prevents the vacuum effect that creates heat explosions. Place a towel over the top of the machine, pulse a few times then process on high speed until smooth.