Ingredients:
100 gms fresh ginger
1 cup lime juice
1 cup water
2 tbsp. water
2 cups sugar

Method:

Wash, peel and grind ginger to a fine paste.
Add 2 tsbp. water, pass through a clean muslin cloth to extract juice.
Dissolve sugar in one cup water on low heat.
Add ginger and lime juice after sugar has dissolved.
Heat till mixture boils (approx. 5 minutes).
Remove from and heat and cool till warm.
Pour into clean sterile bottle.
Refrigerate and use as concentrate, when required.

To Proceed:
Add 3 tsbp. of concentrate to 300 ml. chilled water.
Whiz with an electrical hand blender, till frothy.
Serve immediately. 

Note: Make sure you dissolve the sugar and water on low heat while making the concentrate, or the sugar might start settling down when refrigerated if boiled on very high heat.