Evenly slice the yams, the thinner they are the faster they will dry, and set aside.

Heat cranberries and water to boil. Reduce heat to medium, and boil gently 10 minutes.

Remove from heat and mix in spearmint leaves.

Place sweet potato slices into the cranberry marinade, add additional water if it's needed to fully cover. Allow to marinate for at least an hour in the refrigerator.

Preheat oven to 250 degrees fahrenheit.

Place on a cookie sheet 1/4 inches apart, brush with marinade for additional flavor and sprinkle with cinnamon.

Dry in an oven, with the door slightly open to let out moisture, for about 3 to 4 hours until you have achieved the texture you want.

Cool and refrigerate.