Take a glass of water, add the jaggery powder and boil for a couple of minutes.
This will help in getting rid of impurities. Let it cool.
Once it cools, strain it. Then fill up half a glass with this jaggery water. Squeeze in the lemon juice.
Add the roasted jeera powder and black salt as per the taste. Fill up the glass with chilled water. Mix well.
Add some ice and mint leaves while serving.