Cucumber Soup

1 tablespoon extra-virgin olive oil
2 cloves garlic, minced
1 small onion, diced
1 tablespoon lemon juice
4 cups peeled, seeded and thinly sliced cucumbers, divided
1 ½ cups vegetable broth or reduced-sodium chicken broth
½ teaspoon salt
¼ teaspoon freshly ground pepper
Pinch of cayenne pepper
1 avocado, diced
¼ cup chopped fresh parsley, plus more for garnish
½ cup low-fat plain yogurt

Heat oil in a large saucepan over medium-high heat. Add garlic and onion; cook, stirring occasionally, until tender, 1 to 4 minutes. Add lemon juice and cook for 1 minute. Add 3 ¾ cups cucumber slices, broth, salt, pepper and cayenne; bring to a simmer. Reduce heat and cook at a gentle simmer until the cucumbers are soft, 6 to 8 minutes.

Transfer the soup to a blender. Add avocado and parsley; blend on low speed until smooth. (Use caution when pureeing hot liquids.) Pour into a serving bowl and stir in yogurt. Chop the remaining 1/4 cup cucumber slices. Serve the soup warm or refrigerate and serve it chilled. Just before serving, garnish with the chopped cucumber and more chopped parsley, if desired.