Preheat oven to 350F. Grease a 12 cup bundt pan with butter or spray with baking spray.
In a cup mix saffron, turmeric and hot water together and let it steep for 15 minutes.
Add buttermilk, vanilla, orange juice and zest to the saffron mixture and mix well.
In a large bowl, combine in flour, salt, baking powder and baking soda
Cream butter and sugar until fluffy and pale.
Beat in eggs one by one then add the yolk.
Add flour mixture alternating with saffron mixture mixing after each addition.*
Pour batter into the bundt cake and bake for 50 minutes until a toothpick inserted in the middle comes out clean
Let the cake cool for 10 minutes in the pan then let it cool completely on a wire rack.
Whisk glaze ingredients well then pour over the cake
Decorate with some chopped pistachios.