Ice tea is a summer classic, perfect for those sweltering days where another glass of water just won't do, but you definitely don't want to go thick and carbonated, like soft drinks, or move into cocktail territory just yet.
And the classic method for making it happen when it's hot? Why, the sun, which,in theory, heats the water without having to warm the kitchen or house with a burner or, back in the old days, hearth fire. "It's also possible that the warmer water actually changes the shape of some of the flavorful molecules in the tea, creating flavors that simply don't exist from colder extractions. Finally, it could be that the light from the sun itself could be changing some of molecules in the tea—giving it a sunburn, if you will—affecting its flavor."
Turns out, at least in one experiment, none of that's really true. Or, at least, if it is, it doesn't make for better iced tea.
But here's the surprising part: between the actual sun tea, the shade tea, the countertop tea, and the refrigerator tea, there was very little difference in flavor extraction. The fridge tea was slightly paler and more dilute in flavor than the actual sun tea, but by letting the bags steep for just one more hour in the fridge, I achieved the same basic level of extraction as the tea steeped in the sun.
The difference was that the fridge-tea tasted better. Cleaner, fresher, with a balanced acidity and very slight bitterness.
Get the how-to, recipe, and more details at Serious Eats - The Food Lab: For The Best Sun Tea, Forget The Sun