Make dough for a single crust pie, and set in the fridge to chill.
Preheat BBQ grill to 400°F (205°C). Place a large reusable aluminum lasagna pan upside down on the grill while preheating.
In a medium bowl, place fruit, sugar, cinnamon, nutmeg, and lemon or lime juice. Mix with a spoon or rubber spatula to combine. Set aside.
Roll out dough to approximately a 12” (30 cm) circle, and place in a 9” (23 cm) disposable aluminum pie pan. There will be about a 2” (5 cm) overhang.
Place fruit filling in dough evenly.
Fold the overhang towards the middle of the filling, making pleats as you go. There should be an opening in the center showing the fruit. Sprinkle with demerara sugar.
Place filled pie pan on top of the pre-heated lasagna pan.
Close the grill top, and bake for 20-30 minutes, checking frequently. It is done when the crust is brown and the fruit is bubbling.
Cool and enjoy with ice cream.