Make /var a indepandant zfs

hi all,

i am wondering the best way for geting out /var from / fs in my rpool.

actualy i have /var under / file system
i whant to have /var in his own zfs in rpool

may be a send recieve betwen a temp pool may work but ??? i am not sure
may be convert the directory in zfs, in dont see a exemple on the web

I know the probable issue with /var/tmp , but i can restart my m4000 after, a new /var/tmp can be hot created during migration ?

sorry for the english level but this is not my mother language.

in advance tank's
sylvain