In a heatproof pitcher, combine the tea bag with the boiling water. Brew for 5 minutes. Remove the tea bag and add the brown sugar. Stir to dissolve, then and add 2 cups cold water.
Add the bourbon, peach liqueur and lemon juice. Stir to combine, then place in the refrigerator until completely chilled.
Add the peaches to the pitcher. Serve in highball glasses over ice with sprigs of fresh mint and more peaches if desired.
