Pour the milk and heavy cream in a medium sauce pan. Set to medium low, slowly heating to boiling, stirring often. Crush the saffron threads and dissolve them in a bit of the warm milk, then pour the golden liquid back in the saucepan. Add the salt. Set the burner to low heat and stir once in a while you do the next step.
Beat the egg yolks and half the sugar until thick and foamy. Carefully pour this mixture into the saucepan, whisking as you go. Add the rest of the sugar and the cornstarch and keep whisking for at least 30 seconds, still on low heat, until thickened. You should be able to trace a clean line on the back of a dipped spoon.
Pour your custard into a non-reactive, sealable container*, and cool overnight in the fridge, or until it is 40°F (4°C) or less in the freezer.
Once cold enough, add in the rose water to taste before churning in an ice-cream maker, adding the pistachios 5 min before fully done. If you don’t have an ice-cream machine, place your non-reactive container in the freezer and mix energetically every 30 minutes, until the ice-cream is homogenous and frozen.
Serve with a jasmine green tea to complement the flavors and cut through the fat and sweetness of this quite decadent ice-cream!
*Meaning something made of stainless steel, ceramic, glass, or plastic. Enameled cast-iron pots are also safe. Raw cast-iron, copper, steel, or nonstick coated pans might leave a taste or even black streaks in your ice-cream.