Put your loose-leaf tea into a T-sac, and place it at the bottom of your heat-resistant pitcher.
Bring 4 cups of water to a boiling point of 212° F. (If you don't have a thermometer, you can estimate. Once the water comes to a rolling boil, you should be at your desired temp of 212° F.)
Carefully pour the hot water into the pitcher over the tea-filled T-Sac, ensuring that the tea is covered with water completely. Steep for 7-10 minutes.
Remove the T-sac from the pitcher.
Add 1/4 - 1/2 cup of the simple syrup to the tea, plus 4 cups of room temperature water. (You can adjust sweetness as you go). Stir well. Set any extra simple syrup aside.
Allow the tea to cool on the counter, at room temp, for about 10 minutes.
After that, add the vodka and stir well.
Finally, add the ice, and place the pitcher in the refrigerator. (This allows the tea to cool gradually. Cooling your tea too quickly will result in a cloudy tea, but it doesn't affect the quality or taste. So, if you do want to quickly cool your tea and you end up with a cloudy tea, don't fret; sip away!)
Prior to serving, you can rim some glasses with sugar (optional), fill them with ice, and toss in some fresh sprigs of mint. Pour in the iced tea, and garnish with lemon wedges; add edible flowers if you have them.
See notes about extra sweetening.