SC - Russian Birch Beer?

[Jeff Gedney]

> 
> I've never heard of the roots being used, but birch sap is often used in
> wine/mead making.
> The actual composition of the sap is unknown to me, but I've read that the
> Vikings drank it after winter, suposedly for it's sugar/nutritional content.
> I'll try and dig up a recipe if you like.
Please do. I'd love any such recipes. 
I got the impression that this was indeed a sap product, But I do not have 
the exact wording with me.
How was the sap obained? By tapping? By crushing and steeping? Or by 
some other method?

Brandu