Method : Take a big sieve ( just like the one used to filter tea ) & pour dahi into that sieve.Leave the sieve with dahi, suspended, to the edges of a vessel ( patela ).Leave it overnight.Cover the dahi in the sieve with a plate or lid.This is done, so that, all water keeps trickling down.By morning ,there will be a semi solid mass of dahi left in the sieve.
Another method is to put dahi on to a thin cotton cloth & tie up the cloth with knot & suspend it from a stand.This helps the water in the dahi , to get separated from the dahi.
12 hours suspension is enough to drain water -hence keep it overnight.
The water along with a little dahi which has collected in the vessel below the sieve can be consumed as chaas.
Take this dahi mass & add sugar to it.Mix this nicely.Now add powdered cardamom to it.Take kesar strands & soak them in milk & add the kesar also to this mixture.