Start hydrating yeast in 1/2 cup of water. Shred ginger in food processor. Boil water. Add everything (except yeast of course) to the boiling water, and simmer for for a bit (say 1/4 to 1/2 hour).
Cool, and add yeast.
Let start in the fermenter for one day, then strain and bottle.
Let the bottle sit in a cool place for a few days, then test one. Be very careful not to let them sit too long -- six days after bottling, one of these blew up in my (Tofi) basement. (This is the first bottle-bomb I've had in about ten years.) I was very careful with the rest of the bottles; moving them into the 'fridge (to arrest the fermentation and dissolve more CO2 back into the pop) and opening them very carefully.
Tofi Kerthjalfadsson, guildmaster, BMDL Brewers' Guild.