Mix together brown sugar, cornstarch, salt, cinnamon, apricot nectar, water, and orange peel in a saucepan; bring to a boil over medium heat. Reduce heat to medium-low, and cook for 2 minutes, stirring constantly. When the sauce is thick, stir in the butter and pecans. Place the sweet potato chunks into the prepared baking dish, and pour the sauce over to coat all the potatoes.