Wash the mint leaves and tap dry on a cloth. Wash the ginger and scrub it well. Grind both of them together.
Take a bowl, add water and mix in the sugar. Put the mint ginger paste, black salt and the lime juice and give a stir. Keep it in the refrigerator for atleast two hours. The flavours of mint infuse with time.
Later, strain it using a thin metal sieve or strainer.