Peel the apples, and cut into 8 equal portions. Remove the core and slice into 5-mm quarter-rounds. Peel the sweet potato and slice it into pieces the same size as the apples.

Add the ingredients from Step 1 into a pan, cover and simmer over low heat. Once the apple becomes transparent and sweet potato is tender, add the beet sugar and mix until dissolved.

Combine the cake flour and salt in a bowl. Pour in the oil and work it into the flour using both hands. Add the apple juice and mix. Be careful not to knead the dough too much.

Bring the mixture of Step 3 together and divide it in half. Place the dough onto parchment paper and cover with a sheet of plastic wrap. Thinly roll out both portions of the dough with a rolling pin.

Lift one sheet of dough into a pie plate. Pierce the bottom edge of the crust with a fork. Pour in the Step 2 filling. Cut the other sheet of dough into strips and lay them over the filling to make a lattice.

Bake in a preheated oven at 200℃ for 15-20 minutes. Reduce heat to 180℃, and bake 20 more minutes. Brush the maple syrup on the surface, then it is done.

If this the lattice is too much of a hassle, you can simply place the second dough on top and make a cross cut in the center with a knife and bake it.