Sarsaparilla, a prickly stemmed vine native to Central America, has flavorful stems, roots and leaves, and is used for root beer and sarsaparilla soda. Traditionally, sarsaparilla soda used fermentation by yeast and sugar for creating bubbles, as did all sodas. These beverages bore the title of "small beers" because they had tiny amounts of alcohol. With the advent of carbonation, fermented soda waned and was replaced by fountain beverages as we know them today.
Put 2 cups of water and 1 cup of sugar in a small pan. Bring this to a boil, stirring until the sugar dissolves completely. Let this cool to room temperature.
Bring the water and sugar mixture to a boil, stirring until the sugar dissolves completely. Let this cool to room temperature.
Pour the two 1-liter bottles of sparkling water or club soda into a mixing bowl or pot. Add them slowly. Save the bottles to refill with the finished sarsaparilla.
Stir in the room-temperature sugar and water mixture, a little at a time. Taste for sweetness. You do not have to use all the sugar syrup. You may also make more simple syrup if it's not sweet enough for your taste.
Add up to 1 tablespoon sarsaparilla extract, adding a little at a time and tasting as you go. Adjust the quantity to your taste.
Use a funnel to pour the sarsaparilla soda into the bottles and cap tightly. Refrigerate and use within three days.