Bring water to a boil on high heat in a medium-size saucepan.
Once the water comes to a boil, switch off the heat. Add loose green tea (or 2 tea bags) to the pan and give it a gentle stir.
Cover the pan with a lid and let the tea steep for 1 minute. Do not steep for more than a minute otherwise, it will turn bitter.
Strain the tea using a tea strainer in a pitcher (jug) and let it cool down to room temperature.
Once the tea is cooled, add mango puree, sugar, and lime juice, and stir until sugar is dissolved. If you like your tea sweeter, add more sugar.
Fill 4 tall glasses with ice and pour the tea over the ice. Garnish with fresh mint leaves and serve chilled. You can also add a lime slice to the glass.