Pour the boiling water over the tea bags in a heatproof container and let steep for 5 minutes. Remove the tea bags and allow the tea to cool.
Combine the sugar with 3 cups water in a measuring cup or bowl and stir until the sugar dissolves to make a syrup.
Pour the lemon juice into a vat or large pitcher, add the syrup and tea and stir. Add the lemon slices and mint springs. Chill for an hour or so to let the flavors develop, then serve.