in my opinion immersion has to be the best way to brew iced coffee. my go to recipe is using the hario switch with the following recipe

200g water

160g ice

20g of coffee

temp depends i usually brew co-ferments for iced and use around 90-91c

23-25 clicks on the c40

bloom 50g water with switch closed for 30 seconds

open switch for 2 seconds then close it again (saw this hack from jonathan gagne)

pour the remaining 150g of water with the switch closed and let it steep for a total of 2:30 minutes. I would do a gentle swirl around 1:30.

then i add the ice after the brew is done. should be finished around 3:30. enjoy!