Sous Vide Lamb Stew

[scarletbagonia]

I know this sounds crazy... but I've been reading the Alinea cookbook, so blame Grant Achatz, haha :)

I just got a new Sous Vide and vacuum sealer and I want to start trying some funky stuff. I'm going to vacuum seal each part of the stew individually with herbs and such to impart unique flavor so...

QUESTION #1:
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What herbs, spices, zests, or flavors in general pair well with:
Celery Root
Carrot
Russet Potato
Lamb
Butternut Squash

Also I HAVE to use Guinness since I'm serving in on St. Paddy's Day so I was thinking of making a marinade for the lamb with Guinness and vanilla bean... too weird?? If not, what other flavors would complement the vanilla and Guinness as well as the lamb?