Put the sifted flour, baking powder, oil, milk, grated orange rind, saffron, sugar, eggs, and a pinch of salt into a mixing bowl and beat together thoroughly until all the lumps are gone and the batter is smooth and thick.
Grease a shallow rectangular baking pan and pour in the mixture.
Bake for half an hour.
Sprinkle plenty of icing sugar on top.
If you prefer it sweeter, you can slice the cake in two (horizontally!) and fill it with whatever you like (whipped cream, chocolate icing, etc).