1Heat coals or gas grill for direct heat.
2Peel sweet potatoes; cut into 1/2-inch diagonal slices. Heat 1 inch water (salted if desired) to boiling in 3-quart saucepan. Add sweet potatoes. Cover and heat to boiling; reduce heat. Simmer about 12 minutes or until almost tender; drain. Mix butter and salt.
3Grill sweet potato slices uncovered 4 inches from medium heat about 20 minutes, brushing frequently with butter mixture and turning once, until tender.
4To serve, sprinkle coconut over sweet potatoes.