1.5 oz ginger root (not the powdered stuff)
6 oz sugar
2 T lemon juice
Water to make 2 liters.
Yeast, approximately 1/2 tsp. (Pasteur Champagne wine yeast works best, but you can use regular bread yeast, too. It just has a yeastier flavor.)
Slice and dice the ginger root as fine as you can, or run thru a grater. Add to the water and lemon juice. Heat on the stovetop until it just about comes to a boil. Cover and allow to steep until it reaches room temperature. Strain thru a piece of muslin or several layers of cheesecloth. Sprinkle yeast across the surface and allow it to dissolve. Whisk to aerate, the yeastie-boys will need a little oxygen to kickstart.
Pour into a 2 liter plastic bottle and screw cap down tight. Let sit at room temp for about 24 hours. Test the bottle by squeezing. At first, it will be fairly easy to dent the sides. By the time it is carbonated, it will be much firmer. Refrigerate and serve. Do not store for more than two weeks, even in the fridge the fermentation will continue and pressure will eventually overwhelm the bottle (don't ask me how I know this).
You can adjust the amount of sugar as you like to vary the sweetness. You can also add more ginger if you like the bite. I almost double the ginger in this starting point recipe, but it is personal taste. My next batch will be made with apple cider and ginger, just for kicks and giggles.