Boil 2 cup water with 1 cup sugar to form sugar syrup. Add lemon juice in it.let it simmer at low heat.

Mix cornflour with water without lumps.it's texture will be thick.add water slowly in cornflour to aquire perfect mixing

Either add food colour in cornflour mixture or add in sugar syrup. Both will be fine as later on both will be combining altogether.

Heat ghee in pan.add cornflour mixture in pan & stir continuously.to avoid lumps.as it gets thick it vl be hard to stir spoon but keep on stiring.

Add sugar syrup gradually in pan. With stirring.heat should be low -medium.slowly add all sugar syrup in pan until all mix well in form of smooth paste. If required u can add little more ghee.

Add some chop nuts at this time with cardamom powder.as till now all mixture in pan is coming together & will be having shine on top.it will leave sides of pan and come together.

Grease a bowl or tray or platter with some ghee.pour thick mixture of halwa in it.sprinkle rest of the nuts & melon seeds over it.spread out evenly.let it cool down at room temperature for quite sometime until it solidify in shape.

When halwa is cooled.cut in desired shapes with sharp knife.serve any time & enjoy the lovely jiggly flavour of yummy Karachi Halwa.