Take a blender and add yogurt in it (yogurt should be made from whole milk)

Than add sugar (you can increase or decrease according to your taste), add pinch of salt

Blend both the things so that sugar dissolve completely

Now add cold milk into it

Add ice cubes as much as u want and add water as well. blend till Lassi become fluffy

Don't blend too much to avoid seperation of fat from yogurt and milk

Serve cold