Preheat the oven to 350 degrees F. Grease the bottom and sides of an 8x11 inch gratin or baking dish.
Peel and core the apples. Slice and toss into a bowl. Sprinkle with lemon juice and toss to coat. Add the maple syrup and stir. Dust with tapioca starch and stir again to coat the slices. Pour the slices into the prepared baking dish.
In a mixing bowl, combine the quinoa flakes, GF flour, brown sugar, cinnamon and salt and whisk to blend. Add the coconut oil in pieces and using a whisk or a pastry cutter, cut the coconut oil into the flour blend until you have and even, sandy mixture. Spoon the mixture over the top.
Bake in the centre of a pre-heated oven, about 20 minutes. Cover the top loosely with a piece of foil and continue to bake for another 20 minutes or so (depends on apples), until the apples are fork tender and the sides of the crisp are budding. The foil will help keep the top from browning too much.