This recipe came from the Christchurch press a few years back and is meant to make excellent ginger beer - haven't tried it myself. It doesn't need a bug to start it.
2 Tbsp warm water
half tsp sugar
1/4 tsp dried yeast granules
1 cup sugar
juice 2 lemons
rind of 2 lemons
1 tsp to 1Tbsp dried ginger
Put first measure of sugar in warm water top dissolve, add yeast and stir. Place in warm place to start working.
finely grate or slice rind from 2 lemons and place in a heatproof container with the 1 cup sugar and dried ginger.
Pour over 1 cup boiling water and leave to steep for 10 minutes
Strain into 1.5L plastic bottle in which the ginger beer will be made
Top up bottle with cool water to near top so that final temp is approx body temp.
Add yeast to bottle as soon as it shows signs of working ie it foams.
Cap bottle tightly.
Mix thouroughly and put in a warm place.
Leave until bottle becomes undentable. Depending on the yeast this can take anything from 12 hours to 3 days but best to check regularly, as there is a risk of explosion with this!
Refrigerate until thoroughly chilled and open with care!