Lightly coat the bottom of your pan with olive oil, or a combination of olive oil and butter, and saute the onions for about 8 minutes until soft and translucent, but not browned. Add the garlic and cook a minute or two more. Add the rest of the ingredients and stir well to combine. Bring up to a simmer, then lower the heat, cover, and cook for 15-20 minutes. Remove the cinnamon stick and puree the soup. Return to the pan and season with salt and black pepper to taste.
