Combine the sugar, mint (stems and all) and 1 cup water in a small pot. Bring to a boil over medium-high heat, stirring to dissolve the sugar. Reduce the heat to medium low and simmer 5 minutes. Remove from the heat, cover and let steep 30 minutes. Discard the mint; refrigerate the syrup until ready to use.
Put 2 quarts water in a pot and add the tea bags. Bring to a boil over medium-high heat, then remove from the heat, cover and let steep 20 minutes. Discard the tea bags. Pour the tea into a pitcher and add the mint syrup to taste. Refrigerate until cool.
Serve the tea over ice. Garnish with lemon and mint, if desired.