* I used a 1/2 teaspoon of cayenne pepper and it gave the whole batch of soup a spicy kick. If you don't like any spice consider reducing or omitting this ingredient. If you like your food spicy you can also experiment with adding more cayenne pepper (this can be done slowly after the soup is pureed).
**If you don't have a crockpot, or don't have all day, you can also cook this soup on the stove. Sauté the onions with a little oil until soft, add the rest of the ingredients except the milk and yogurt, then bring to a boil and simmer until everything is super tender. Jump back to the directions for adding in the milk and yogurt and pureeing until smooth and delicious. Easy as, well, soup!