In a saucepan, bring 2 cups of water to a boil.
Remove from heat and steep the tea bags for 5–10 minutes.
Discard tea bags and allow tea to cool slightly.
In a blender, puree the mango pieces with the remaining 2 cups of water until smooth.
Strain the mango puree through a fine mesh sieve into a pitcher.
Add the brewed tea, lemon juice, and sugar (if using) to the pitcher and stir well.
Chill in the refrigerator for at least 1 hour.
Serve over ice and garnish with mango slices and fresh mint leaves.