I regularly make stocks and broths and I have always made them without salt. I always belived I could just add it later in whatever amout was appropriate for where it was being used. Especially since I occasionally boil a stock down to double strength to give a dish a jolt of flavour, no salt seemed to be the right way to go. Lately, however, I've read a couple of recipes for stocks that claim that salt is necessary for full extraction of the flavours. What do you think? If you think salt is essential, what is the least amount you can use for the salt to do its job?