Start by peeling the mandarin or clementine orange and separating the segments. Remove any visible seeds to ensure a smooth blend. Measure the frozen mango chunks so the smoothie will have the perfect balance of citrus and tropical flavor.
Pour the water into the blender first, followed by the Greek yogurt. Add the orange segments, frozen mango chunks, ground flaxseed, and vanilla extract. Adding the liquid first helps the blender process the ingredients more efficiently.
Blend the smoothie on high speed for about 45–60 seconds until completely smooth. The mixture should become thick, creamy, and evenly blended. If you prefer a colder smoothie, add ice cubes and blend again briefly.
Pour the smoothie evenly into two glasses. Garnish with orange slices or a sprinkle of flaxseed on top. Serve immediately while chilled and creamy.