Preparation / Directions:
Scrub sweet potatoes well. Place in a large pot and cover with cold water. Bring water to a boil, reduce heat, and simmer until almost tender, about 40 minutes (they should be a little undercooked). Remove from heat and drain; peel and set aside. (Sweet potatoes can be prepared 1 day in advance up to this point.)
Combine balsamic vinegar and sugar in a small saucepan over high heat. Simmer mixture until it is thick and syrupy, or reduced by one-half, about 10 minutes. Remove from heat, add butter and cool.
If using grill, heat grill to high. Cut sweet potatoes crosswise into 1/2-inch-thick slices. Brush tops of slices with oil and place, brushed side down, on grill until marked, about 2 minutes. While slices are cooking, brush the other sides with remaining oil and turn over.
Grill until marked, about 2 more minutes. Brush grilled sweet potatoes on both sides with vinegar glaze and serve.
If using grill, heat grill to high. Arrange sweet potatoes slices on a baking sheet and brush tops with glaze; no oil is necessary. Place baking sheet under grill and grill until glaze starts to bubble, 3 to 4 minutes. Remove from oven, turn potatoes over, and brush with glaze.
Grill for 3 to 4 more minutes.
Recipe By: Martha Stewart Living November 1994