If using the oven, preheat to 425 degrees.
Cut off the ends of the sweet potato. Then stand the sweet potato up on it's end and cut in half length-wise. Take one of the halves and cut it into long slices to desired width (I usually aim for a 1/4 of an inch, but it's not an exact science). Try to keep slices uniform in width so they will cook evenly.
Lightly toss or brush slices of sweet potato with oil on both sides. Just a little, don't drown the potato in oil, or your toast will be soggy.
If baking, line a baking sheet with parchment and lay out potato slices in a single layer. Bake for 10 minutes at 425, until tender, then broil on each side for 5 minutes (flipping to get both sides)
If airfrying cook at 375 for 10 minutes (or at 325 if you have an airfryer like mine that runs hot). Make sure they are in a single layer, and flip once.
Freeze in a single layer then store in the freezer in a sealed bag or container for up to 3 months. Toast or airfry to reheat.