In a thick bottomed pan over medium-low heat caramelize the onions with the olive oil, stirring often (saute for a long period of time to release the natural sugars). This will take about 15 to 20 minutes so be patient. Use small amount of water to help release the sugars that will stick to the bottom of the pan. Add all other ingredients and bring up to a warm temperature*. Remove from the stove and puree with a hand blender or food processor. Season with salt and pepper.
*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.
