In a medium bowl, combine cornflour, baking powder and salt.
In a food processor, combine cornflour mix with cubed cold butter. Pulse until it resembles coarse breadcrumbs. Set aside.
In a bowl, combine white rice flour with sugar and yeast. Add to food processor and mix till just combined. Add 5 egg yolks and pulse until a soft dough ball is formed and easily separates from the walls. Wrap in cling film and chill for 30 minutes.
Remove pastry dough from the fridge and let stand at room temperature for 15 to 20 minutes.
In the meantime, preheat oven to 180 C / Gas 4. Line a 23cm tart tin with parchment.
Roll out 2/3 of the dough and press into the bottom and sides of the tin. Spread a thick layer of quince jam.
Take half of the remaining dough and cut with a pastry wheel or sharp knife into strips, 2cm wide, and lay on a baking tray and freeze 5 minutes. Lay dough strips in a lattice pattern on top of the quince filling, cutting off the excess. Take remaining dough and roll into a snake, then use to line the edge of the tin.
Bake in the preheated oven until golden, about 30 minutes. Remove from the oven and let cool on a wire rack. Dust with icing sugar once at room temperature and serve.