Sift together dry ingredients. Beat eggs until light. Add honey gradually and continue beating until well mixed. Beat in mashed banana, butter, sour cream and vanilla. Stir in flour mixture. (Dough should be soft.) Chill 2 hours or longer. Roll out on floured board about 1 cm thick. Cut with doughnut cutter. In deep fat heated to 190ºC , fry a few at a time. (Fry the holes as well as the doughnuts.) Turn doughnuts when they rise to the surface and are brown on the underside. Fry until brown on both sides. Remove from fat and drain thoroughly. Note: May form into long rolls and twist together to form crullers, cutting off every 5 cm.