Stir 1 teaspoon sugar into warm milk and sprinkle with yeast.
Let stand 5 minutes or until the surface is frothy.
Stir gently to moisten any dry particles remaining on top.
Sift flour and salt into a large bowl.
In a medium bowl, beat butter, remaining sugar, eggs, lemon and orange peel.
Stir in yeast mixture; add to flour mixture, combining to make a stiff dough.
On a floured surface, knead dough a few minutes.
Cover and let rise in a warm place 15 minutes.
Simmer raisins and currants 2 minutes in a little hot water; drain.
Knead into dough with candied orange peel.
Let dough stand in a warm place 30 minutes.
Heat oil for frying to 320°F (160°C) in a deep-frying pan.
Using 2 floured tablespoons, form dough into small doughnuts.
Add about 6 doughnuts at a time to hot oil.
Fry about 10 minutes or until golden brown, turning halfway through cooking with a slotted spoon.
Lift out cooked doughnuts with slotted spoon; drain on paper towels.