Makes about 10 cups.
To make soup base, combine
Place all the ingredients in a large pot. Cover and bring the liquid to a boil, reduce heat to low and simmer with lid slightly tilted for 40 minutes, or until peas are tender and the soup has thickened. Stir occasionally.
Puree half of the soup base in a blender if you prefer a smoother textured soup. Return the puree to the pot for the final step, which is to add:
Continue to simmer soup with lid closed for another 15 to 20 minutes. Stir in 1 tablespoon of olive oil (optional). Taste the soup, correct seasonings and add water or vegetable broth if soup is too thick.