6 lemons (preferably organic), zested and juiced
1 1/2 to 2 cups sugar
1 gallon of water
1/8 to 1/4 tsp yeast
1. Zest the lemons (I peeled off the yellow part of the peel with a potato peeler so the pieces were large and easy to strain out). Bring to a simmer with the sugar and half the water in a large stockpot.
2. rehydrate the yeast in about 1/4 cup of the remaining water, at room temp.
3. After the lemon flavor is infused into the simmering mix (it will turn yellowish from the lemon oils), turn off the heat, add the lemon juice and the rest of the water to cool the mixture. When it is cool to about 100 decrees Fahrenheit, add your yeast and immediately bottle in sterilized bottles.
4. Keep in a dark place at somewhere around 70 to 75 degrees. Check after 2 days, then again after 3. Open over the sink in case the soda is extra-carbonated. I made mine less sweet, on purpose, with 1 1/2 cups sugar. A typical soda recipe would call for 2 cups.
I like to use bail top bottles for mine, supposedly they are stronger and better able to stand up to excessive carbonation. If you've never made soda before, I'd recommend looking up more instructions and details from experts (I'm not one).
My first attempt at this I included vanilla, but the flavor of vanilla was completely lost in the final product- I think fermented sodas are better with bold flavors rather than delicate nuances, at least in my experience so far.