In a soup pot heat oil. Add onions and sauté 4-5 minutes. Add garlic and cook 1 minute. Add red peppers and broth and bring to a boil. Reduce heat and simmer soup 30 minutes. Meanwhile combine yogurt and pesto until smooth.
Blend soup until smooth. Add 1/4 cup yogurt pesto to soup and mix well. Ladle soup into bowls and top each with a dollop of pesto yogurt and serve.