I used to slice it nearly paper thin, using a mandoline. Then I'd spread it out, not caring if the slices overlapped somewhat, on a solid dehydrator tray (the ones used for fruit leather). I'd stir them up pretty regularly for the first bit, otherwise they'd just fuse onto the tray as they dried.
Once they were fully dry, I'd powder them up in a coffee grinder to make bouillon powder.
Slices should dry just fine in a car or warm room IF the humidity is low enough. It would take forever to do it here, except for a few days a year.