Combine 1/2 cup boiling water, saffron, and 1 pinch salt in a small bowl; steep for 8 hours to overnight.
Crumble yeast into a small bowl; add 1/4 cup warm water and 1 pinch sugar.
Mix 1 cup sugar, 1 1/2 teaspoon salt, and nutmeg in a large bowl.
Heat milk in a small saucepan over medium heat until it begins to bubble, about 5 minutes. Remove from heat; allow to cool for 5 minutes.
Beat saffron water, scalded milk, shortening, lemon extract, and lemon zest together in a bowl. Add eggs; stir to combine.
Pour yeast mixture and milk mixture into sugar mixture; mix well. Add flour 1/2 cup at a time; mix after each addition until incorporated. Stir in raisins and currants. Knead dough well; transfer to a greased bowl and cover with plastic wrap. Allow dough to rise until doubled in size, 1 to 2 hours.
Preheat oven to 350 degrees F (175 degrees C). Grease two 9x12-inch baking pans.
Turn dough out onto a lightly floured surface; divide in half. Form each half into 12 equal balls; arrange in prepared baking pans. Allow dough to rise again, 30 minutes to 1 hour.
Bake in the preheated oven until golden, about 30 minutes.