Method
Our ginger beer recipe is a one-step fermentation. However, it requires preparing in advance a "ginger bug", a very concentrated yeast and good bacteria environment that will be able to outcompete all other "bad" bacteria when we brew the beer later.
Ginger bug
First, cut half of the ginger into 1 cm cubes, keeping the skin. That's where the good bacteria are. Set aside the other half.
In a jar of ½ litre, add the cut ginger and 2 tablespoons of sugar, then fill half of the jar with filtered water. Never use water straight from the tap as it contains chlorine that will kill the beneficial bacteria necessary for the fermentation process. If you do not have a filtering system, first boil your water, let it cool, and add it to the jar. Loosely close the jar without tightening.
Add an extra 1 cm ginger and 1 tablespoon of sugar the day after, lightly stirring the mixture. Repeat for the next 4 days.
After 5 days, your ginger bug is ready to be used for bottle fermentation. You can keep your ginger bug jar for a while. Ours sits on the kitchen bench. Before using again, add 1 tablespoon of sugar 24 hours before re-activation.
Ginger beer
Collect four 1.5 L plastic bottles. We got ours from our flatmate's sparkling water bottles. It needs to be plastic as the bottle will expand during the fermentation process.
In a large bowl, dissolve the sugar into 2 cups of boiling filtered water. Set aside.
Add the ginger to a food processor or blender, cover with filtered water and process at high speed until pureed.
Add 2 cups of cold filtered water to the bowl to reduce the temperature. You want the dissolved sugar water to be lukewarm or colder to keep the coming yeast and bacteria alive.
Using a cheesecloth, filter the puree in the sugar water. Add half of the mason jar of ginger bug liquid without ginger pieces—you can top up your ginger bug jar with water and add sugar if you want to do another batch later in the week and set it aside.
Your bowl now contains the dissolved sugar, filtered ginger puree and ginger bug liquid. Divide the content between the four plastic bottles at roughly the same level. Top up each bottle with filtered water and screw the cap.
Store the bottles in a warm, dark environment—ideally between 20 and 25 degrees, for 5 to 7 days. Your ginger beer is ready when the bottles are hard, similar to soda bottles. Time to rejoice! Remember to place it in the fridge before drinking to make it fresh.
You will probably see pale, dusty deposits at the bottom of the bottle. That is fine as it is yeast and good for you and your gut. Before serving, gently turn the bottle upside down a few times to spread the yeast goodness in the bottle.
Open ginger beer bottle will keep in the fridge for up to one week. Ours are empty after one hour around. Enjoy!