In a medium saucepan, bring 2 cups of water to a boil. Once boiling, remove from heat and let it cool slightly.
In a blender, combine the diced dragonfruit, diced mango, sugar, lemon juice, and green tea powder. Blend until smooth.
Strain the blended mixture through a fine mesh sieve into a large pitcher to remove any pulp.
Add the cooled water to the pitcher and stir well to combine. Adjust sweetness by adding more sugar if desired.
Chill the mixture in the refrigerator for at least 30 minutes.
To serve, fill a glass with ice cubes and pour the chilled refresher over the ice. Garnish with fresh mint leaves if desired.