(For the sweet potato, you can cook it by baking it for 45 mins in the oven or boiling it in water. once softened you can use it in the recipe.)
Preheat oven to 190C/375F
n a food processor fitted with a blade, add the mashed sweet potato, potato starch, salt, garlic powder and oil. Bllitz it until mushed into a dough-like mush. This can also be done by hand, mushing it together until it is all combined.
Mixture should be combines but not too sticky. If it is sticky, add a little more potato starch (about 1/4cup at a time).
Place dough between two pieces of parchment paper. Use a rolling pin to roll the dough flat to the height of about 1/8th of an inch. If you don't have a rolling pin, press the dough flat with the bottom of a baking pan.
Peel back the baking paper and cut into 1" squares.
Move the baking papers with squared of dough to a baking tray (disposable is fine). Bake for 18-20minutes. Tops should be golden, edges crispy. If your crackers were a little thicker, then you many need to bake it for an additional 5 minutes.
Cool, store in air-tight containers or ziplock bags.