Preparation Cut cucumber into 3 equal pieces, then coarsely chop 2 pieces. Quarter avocado lengthwise, then pit, peel, and coarsely chop one half. Blend together chopped cucumber, chopped avocado, scallions, minutest, buttermilk, water, and 1 teaspoon salt in a blender until smooth, 1 to 2 minutes. Chill soup, uncovered, 15 minutes. Cut remaining cucumber and avocado into 1/4-inch pieces and stir into soup. Season with salt. Thin with additional water if desired.
Preparation Cut cucumber into 3 equal pieces, then coarsely chop 2 pieces. Quarter avocado lengthwise, then pit, peel, and coarsely chop one half. Blend together chopped cucumber, chopped avocado, scallions, minutest, buttermilk, water, and 1 teaspoon salt in a blender until smooth, 1 to 2 minutes. Chill soup, uncovered, 15 minutes. Cut remaining cucumber and avocado into 1/4-inch pieces and stir into soup. Season with salt. Thin with additional water if desired.