Wash the blackberries thoroughly if using fresh ones. Peel the banana and slice it into small pieces so it blends easily. Measure all the ingredients beforehand so the smoothie can be blended quickly and evenly.

Pour the water or almond milk into the blender first. Add the Greek yogurt, blackberries, banana slices, honey, and lemon juice. Placing liquid ingredients at the bottom helps the blender process frozen fruit more efficiently.

Blend the mixture on high speed for about 45–60 seconds until the smoothie becomes creamy and fully blended. If the smoothie is thicker than desired, add a splash of milk or water and blend briefly again.

Pour the smoothie into a tall glass. Garnish with fresh blackberries or a slice of banana on top. Serve immediately while the smoothie is chilled and smooth.