Bring 4 cups water to a boil in a medium saucepan. Add the sugar, and stir until it has dissolved. Let cool for 2 minutes. Add the tea bags, stir and let steep for 3 minutes. Remove the tea bags, and squeeze the liquid back into the pot. Transfer the tea to a container, and refrigerate until cool, about 10 minutes.
Fill 4 highball glasses, Collins glasses or mason jars with ice. Add 60ml-90ml of the whiskey and 240ml of the tea to each. Garnish with lemon slices and dried jasmine flowers if using.