Scrub four good-sized sweet potatoes, leaving the skins on. Bring a large pan of water to boil, add sweet potatoes and parboil for 10 minutes. Drain thoroughly and allow to cool enough to handle. Remove; peel and slice potatoes (1/2-inch thick) and set on platter.

Combine four tablespoons bottled or homemade chili sauce with two tablespoons sunflower oil; add salt, and pepper to taste. Brush chili mixture over potato slices. Put slices oil-side down on the grill over medium-hot coals. Grill 5-6 minutes. Turn slices over and brush with sauce. Repeat grilling process.