[Split from thread discussing local sources of persimmons on the S.F. board]
If you do get unripe Hachiya persimmons, you can also peel, core and slice them about 1/2" thick, then dry them in a dehydrator for about 18 hours at 135 degrees. They aren't as special as hoshigaki, and they don't have the crystallized sugar on the outside from the massage, but it makes a great dried fruit, and it's a great way of using up large quantities of Hachiya persimmons without having to wait until they turn into water balloons (the tannins disappear in the drying) or resorting to recipes that start "Cream one stick of butter with 1 cup of sugar."
The other non-buttery way is to freeze the fully-ripe ones into a sorbet.