7 gm (1 sachet) dried yeast200 ml warm milk90 gm caster sugar2eggs60 gm butter at room temperature, chopped530 gm plain flour, plus extra for dusting½ tsp vanilla extractVegetable oil, for deep-frying220 gm (11/4 cups) pure icing sugar, sieved3 tbsp lemon juice Quince and apple filling350 ml apple cider200 gm caster sugar1 cinnamon quillJuice and thinly peeled rind of ½ lemon2 quince (about 370gm), peeled, cored and cut into 2cm dice30 gmbutter, chopped, plus extra for buttering bowl3Granny Smith apples (about 400gm), peeled, cored and diced2 tbsp brown sugar
Stir yeast and warm milk in a bowl until yeast dissolves and stand until foamy (5-7 minutes).
Place sugar, eggs, butter, half the flour, vanilla, yeast mixture and 1 tsp fine sea salt in an electric mixer fitted with a dough hook and knead on low speed to combine, then add remaining flour and knead until a sticky dough forms (4-5 minutes; dough will be quite wet). Turn out onto a lightly floured surface, dust top with a little extra flour, form into a ball, transfer to a lightly buttered bowl, cover with plastic wrap and set aside in a warm place until doubled in size (1-1½ hours).
Meanwhile, for apple and quince filling, combine cider, sugar, cinnamon, lemon juice and rind and 250ml water in a saucepan, add quince, reduce heat to low and simmer until quince is tender (50-55 minutes). Strain and cool. Heat butter in a frying pan, add apple and brown sugar, and cook, stirring, until caramelised (12-15 minutes). Add quince, toss to combine and cool.
Roll out dough on a floured surface to 24cm x 40cm. Scatter with half the filling, fold in thirds to enclose, turn so shortest side faces you and roll again to about a 24cm x 40cm rectangle. Scatter with remaining filling, fold in thirds again and roll to a 24cm x 40cm rectangle. Cut into 4cm squares, gather corners and pinch to enclose (if a little filling comes out just press back into dough).
Heat oil to 170C in a large saucepan. Deep-fry fritters in batches (be careful, hot oil will spit), turning once, until golden and cooked through (3-4 minutes). Drain on paper towels and repeat with remaining fritters.
Combine icing sugar and lemon juice in a bowl, then dip fritters in icing, shake off excess, set aside until set (12-15 minutes), then serve.