Witchetty grubs or witchetty spuds ?

Oca...pretty sure about that...mine are now chiiting away...plant out either late april, after fosts have past...or in large buckets/bags mid april , in a G/house.
They can be roasted boiled or even grated raw on salads or even stir fried.
Belive they origionate from Peru or somewhere like that in S/America..

Oh! and upon harvesting they need to be kept on a window cill or somewhere where the light/sun can get to them....something to do with the rippening of them...

Best of luck with them....

Yep definatley oca
Never heard about chitting them before as they can shrivel up a bit if kept too warm. I just put mine in pots last year before transferring outside although they did take 1-2 months to come up. If growing them outside I'd recommend planting them so that you can easily fleece them as you need to keep them alive till mid-late november at least to get a decent crop.
Putting them on a windowsill in the sun helps change the taste from sharp and lemony to slightly sweeter but they can be eaten without that treatment if you prefer them sharper. The little ones (too small to cook) are nice when sharp as an alternative to radishes. Also try roasting with honey-YUM 

One last question. what size pot and how many per pot? Cheers.

Definately Oca.

I bought some this year, had never heard of them before, it's my new crop trial for this year. I've done a fair bit of reading up about them.

They originate in the Andes and are an Oxalis like the decorative plants and have the same type leaves and flowers. Once grown they can be eaten boiled, mashed or fried. Can also be eaten raw, sliced, where they have the texture of a water chestnut but with a tangy flavour.

They can be chitted like potatoes and potted up in 3" pots to bring on until frosts are over.
Planted out at about the same spacing as spuds. They grow a huge amount of foliage which eventually 'crashes', any stems that touch the round will root.

Keep growing as long as possible which may mean protecting from Autumn frosts.

Important Bit When eventually they do get frosted leave them alone. The tubers only swell significantly after the top growth is frosted. Leave for a few weeks then harvest like a potato. They appear to get swell their tubers from the dying top growth.

One downside is that they might release some chemical which might have a detrimental effect on the following crop. It might be a candidate for monculture.

Trikidike...has more or less said all there is to say about Oca...for the reason he/she has said , they may leave toxics or chemicals in the soil, is why I suggested growing them in buckets/bags...
as you would 1st early potatoes...this is what I've been advised to do by others who have grown them in past years....
Start them off in 3" pots transfere to larger flower bucket size, without disturbing the roots too much.