Wash the spinach thoroughly and remove any thick stems. Cut the avocado in half, remove the pit, and scoop out about one-quarter of the flesh. Slice the frozen banana into smaller pieces if necessary so it blends more easily.

Pour the water into the blender first. Add the Greek yogurt, spinach leaves, avocado, frozen banana, and honey. Placing liquids at the bottom helps the blender blend frozen ingredients smoothly.

Blend the mixture on high speed for about 45–60 seconds until the smoothie becomes completely smooth and creamy. If the smoothie is thicker than you prefer, add a little more water and blend briefly again.

Pour the smoothie into a tall glass and serve immediately. For extra presentation, garnish with a small spinach leaf or avocado slice on top.