From the Essential Pépin tv series, Episode 101: Savory Staples
An easy dish, these sliced sweet potatoes are cooked in butter, oil, and water until the water evaporates and they are nicely browned. They are good with almost any meat or fish main course.
1 large long sweet potato (about 1 pound), peeled and cut into 12 slices, about 1/4 inch thick
1 tablespoon unsalted butter
1 tablespoon corn oil
1/2 cup water
1/4 teaspoon salt
Arrange the sweet potato slices in a single layer in one very large or two slightly smaller nonstick skillets. Add the butter, oil, water, and salt. Bring to a boil, cover, and boil gently over high heat for about 5 minutes. Most of the water will have evaporated and the potatoes will be soft. Continue to cook, uncovered, over medium heat, turning, until the slices are nicely browned on both sides, about 2 additional minutes per side. Serve.