Steam four or five large sweet potatoes (or yams, oriental yams--any kind of sweet potato, yam or potato will work) for 25 minutes or boil them for 15 minutes. The goal is to cook them until they are soft but still firm (you should be able to stick a fork into the center). After you take them out of the oven, let them cool overnight in the fridge.

In the morning, bake the same potatoes at 500 degrees for 30 minutes. You'll need to go through the same cooling then baking procedure one or more times, so that the potatoes have been cooked and cooled more than once.

After the potatoes have been cooked and cooled at least twice, slice them thinly and spread them out on a wire cooling mesh placed over a cookie sheet. Put them back into the oven (a convection oven works best) for 20 to 30 minutes, avoid burning.

They should come out crispy and carmelized around the edges but soft and tender in the middle, and you can eat them hot or cold. This recipe requires no salt, pepper or butter, so the potatoes are very healthy yet delicious. Even better if you're dieting, they are completely satisfying. The more times you cook and cool them, the more resistant starch that develops. Click here to learn how important resistant starch is to a human body: https://www.healthline.com/nutrition/resistant-starch-101

Cooking and cooling rice or beans also creates resistant starch.