Heat olive oil in a large soup pot. Add onion and stir, cooking until translucent. Add garlic and saute for one additional minute.
Add all other ingredients to the pot. Bring to a boil and then reduce to a low boil/simmer.
Simmer for 30-40 minutes, or until lentils and potatoes are soft. Transfer in batches to a blender and blend until smooth (or use a stick-blender to blend directly in the pot).
Serve with warm pita bread for dipping.
Notes
Begin with 8 cups of broth, and add additional broth if needed to achieve desired consistency after pureeing. You can substitute vegetable broth for chicken broth if you'd like to make this a vegan soup recipe.