As popularized by Esme Gigi Genevive Squalor, of Lemony Snicket's "A Series of Unfortunate Events" book the 6th.
Recipe inspired by Kathryn Kingsbury's, at http://www.herbcompanion.com/recipes/08_09_05-parsley
You may also want to check out mediaphage's Ginger Ale recipe:
2-Liter Soda Bottle & Cap (clean it well with soap, or a diluted bleach solution)
1 to 2 cups Sugar
Juice of 2 Limes
Yeast (common baker's yeast will work, but wine or champagne yeast is recommended)
1 bunch of fresh parsley
Step 1: Parsley Water
Wash and finely chop the parsley. Place in pot and add enough water to cover. Bring to the boil and let simmer until water absorbs parsley flavor to taste.
Meanwhile, juice the 2 limes. You can boil lime zest along with the parsley if you would like.
Step 2: Strain and Cool
Strain the parsley water into a bowl. Add chopped ice until the water is warm. If it is too hot it will kill the yeast. Add the lime juice.
Step 3: Filter
You can filter out the lime pulp and small pieces of parsley with a coffee filter. It may take quite some time for it all to pass through, so you may prefer just to pour it through a fine strainer a few times.
Step 4: Mix, Bottle, and Shake
Using a funnel, pour your concoction into a plastic 2-liter soda bottle. Add 1 to 2 cups of sugar, and the yeast. Add water until bottle is almost full--leave an inch or two of air at the top. Cap the bottle and shake to dissolve the sugar.
Leave bottle to sit for a day or two until pressure has built up to the point that the bottle does not indent when you squeeze it. Put it in the refrigerator to stop the fermentation. If you let it sit too long, the bottle will explode.
Step 5: Enjoy, Become the Envy of Your Friends and Enemies
The parsley adds a subtle crispness to the soda.
Serve with appropriate panache.