Lumos did a lovely cocoa sourdough with cranberries, walnuts and orange peels for Codruta from the fresh loaf. www.thefreshloaf.com/node/25490/xxi 
visited Tokyo recently in December 2012. there, they have lovely ingredients for all sorts of cooking. especially at the tsukiji fresh market. bought some good green tea powder and black beans.
after looking at the recipe for the cocoa sourdough, i had a thought of replacing the cocoa powder for the green tea powder. and added the black beans instead of the cranberries. yuzu peels instead of orange peels...
this is how it turned out.. beautiful bitter flovor from the tea and sweetness from the black beans quite similer to chestnuts. aromatic yuzu ...yum