Combine the boiling water and sugar in a heatproof container. Stir until sugar is dissolved.
Add the tea bags and steep for 5 minutes. Remove tea bags and discard.
Pour the tea base into a heatproof pitcher or serving jar. Add the cold water, ice and bourbon. Stir well, and refrigerate until serving.
To serve, pour into an ice-filled highball glass or Old Fashioned glass.
Garnish with mint and lemon slices.