Make the shrikhand: Line a large bowl with a double layer of cheesecloth. Pour the yogurt onto the cheesecloth, gather the corners of the cloth and tie into a bundle. Then tie the bundle onto a wooden spoon. Lay the spoon across the top of a pot so the bundle hangs in the pot; drain in the refrigerator overnight.
Empty the thickened yogurt into a bowl; whisk until very smooth. Stir in 1/2 cup superfine sugar, the cardamom, nutmeg and saffron (if using). Taste and add more sugar, if desired. Shrikhand is supposed to be slightly tart. If it's not, add some or all of the sour cream.
Stir most of the raisins and pistachios into the shrikhand; sprinkle the remainder on top. Cover and chill for at least 1 hour.
Make the pooris: Mix the flour and salt in a large bowl. Rub 1 tablespoon vegetable oil into the flour; make a well in the center and gradually pour in 2/3 cup water. Mix with your hands until the dough forms a ball, then knead on a clean surface until smooth but still slightly tacky, about 5 minutes. Cover with a damp cloth and let rest, 30 minutes.
Divide the dough in half; roll each portion into a 1/16-inch-thick round. Cut out about 20 circles using a 2 1/2-inch round cookie cutter.
Heat 2 inches vegetable oil in a large saucepan until a deep-fry thermometer registers 350 degrees F. Line a colander with paper towels. Fry the pooris in batches until golden brown, 1 minute per side. Remove with a slotted spoon; drain in the colander. Serve the hot pooris with the cold shrikhand.
Photograph by Charles Masters
Recipe courtesy Aarti Sequiera for Food Network Magazine