Heat 1/2 cup of the milk in a small pot until the milk is steamy. If you’re using turmeric, add it to the milk. Remove from heat and stir in the saffron threads. Let it cool until it is warm to the touch, but not hot.
Lightly warm the remaining 1/4 cup of the milk. Stir in 1 tsp of the sugar and the yeast into it. Let sit for about 5 to 10 minutes till frothy.
In a large mixing bowl or bowl of your kneading machine, whisk together the flour, remaining sugar, salt, and powdered cardamom. Make a well in the centre of the flour. Add the milk-saffron mixture, frothed yeast, eggs, and yogurt or sour cream.
Start kneading on low speed. Now add the butter and knead some more. Add a little more flour or milk, if required, until the dough is still a little sticky to the touch, but does not really stick to your hands when you handle it.
Shape the dough into a ball and place in a large oiled bowl. Turn the dough so it is well coated and loosely cover. Let rise until double in volume (about 2 hours). At this point you can refrigerate the dough overnight if you wish.
The dough is ready when you poke your finger in it and it takes time for the indentation left by your finger to go away. Gently press it down and knead it a couple of times. Divide the dough into 14 or 16 equal pieces. Work with one piece at a time and keep the others covered so they do not dry out.
Roll each ball of dough into a rope about 12 to 14 inches long. Very lightly dust your working surface with flour if the dough feels very sticky. Too much flour will not give the dough traction and it will be difficult to roll out.
To make an “S” shape, curl the ends in opposite directions, with spirals at each end. Similarly shape the other balls of dough into whichever shape you wish. Place on a baking sheet lined with parchment, leaving enough space in between.
Loosely cover and let them rise for about 30 to 45 minutes till almost double in size. Using a pastry brush, glaze the tops and sides with milk or cream. Press in a raisin or currant in the middle of each spiral, so about 2 for each bun. Sprinkle a little pearl sugar if using.
Bake the buns at 200C (400F) for about 12 to 15 minutes or till they turn golden brown on the top. Let them cool on racks. They’re best eaten when slightly warm.