Make the curd two days before you plan to serve the shrikhand. Boil the milk and set aside till lukewarm. Add the starter curd, stir well, cover and leave it to set at room temperature for 6 to 8 hours or overnight in cooler weather. The curd should have a visible layer of whey on the top to indicate it's fully set. Once done, refrigerate till firm, preferably overnight.
When ready to hang the curd, take a large muslin/cheese cloth, tip all of the set and chilled curd into it, and secure it tightly with a sturdy string. Hang the bundle of curd at a reasonable height, for 8 hours or overnight, till all the whey has drained out. Make sure you have a large vessel underneath the bundle to catch all the liquid.
Once the curd is drained of all liquid, untie the cloth and in a large mixing bowl, add one heaped spoon of the hung curd and one level spoon of sugar, alternately. Use two large spoons to speed up the process, making sure they're the same size. Repeat until all the hung curd is in the bowl. The amount of sugar used is roughly three-fourths of the quantity of hung curd you get.
Using a hand mixer, beat the curd and sugar on medium speed till smooth. Add the saffron and cardamom powder and beat again to combine. The shrikhand should be sweet, with a hint of tanginess. Taste and add a bit more sugar if needed as in warm weather, the curd will be more sour.
Refrigerate for at least 5 to 6 hours before serving. It tastes delicious as is or for a summery touch, add freshly chopped mango on top. For a variation using mango pulp, see recipe notes.
Keep the shrikhand stored in the fridge for 4 to 5 days or in the freezer for longer. Enjoy!