Beat shortening for a few seconds. Add brown sugar & beat till well blended & creamy. Stir in vinegar, bananas, water & lime juice. Ensure that all ingredients are well mixed. Add salt, ginger & grated coconut. Mix well. Stir in baking powder. Sift flour & beat with a wooden spoon till well blended & smooth. Transfer into a greased loaf pan & bake at 350F for 1 hour. Let cool for 10 minutes before removing from pan to a wire rack.
Meanwhile, combine brown sugar, oil, rum & lime juice in a snall pot over a low heat. Stir constantly for 5 minutes until you have a thin syrup. Pour over the loaf, spreading it with a spatula, let it run over the sides.
By Mark Satterly, Adapted from "Sundays at Moosewood Restaurant"