Add yeast to warm water until dissolved. Melt quarter cup butter; add peel and juice and heat to lukewarm. Add sugar, salt and egg. Combine with yeast. Add about half the flour and beat until smooth. Gradually blend in remaining flour. Stir in raisins. Turn out onto floured board and knead lightly about 1 minute, just until dough is smooth. Place in bowl, brush top with melted butter. Cover closely and let rise in warm place about 1 to 1.5 hours until double in size. Punch down, shape into 24 to 30 small balls. Melt 2 tablespoons butter. Dip balls in melted butter, then roll in orange sugar and arrange in layers in greased 23 cm tube pan. Let rise about 0.75 to 1 hour, until doubled. Bake at 180ºC about 1 hour, until golden. Serve warm.