Make batter at least an hour before required, using following method. Sift together flour and salt. Make a well in the center. Add the cooled melted butter and some of the water and egg yolks. Work in the flour and beat until smooth. Add remaining water. Leave to stand. Just before using, beat the egg whites until stiff but not dry. Fold into batter mix. Peel, core and slice apples (slices about 1/4-1/2 inch thick). Dip into batter and deep fry in very hot oil (175-180C) until golden. Drain and serve dredged with sugar and sprinkled with lemon juice.