In Pakistan, sweet potatoes, or shakarkandi as they are called in Urdu, are mainly used in dessert recipes. They are usually very sweet and a pale to rich orange in color when cooked. However sweet potatoes come in various degrees of sweetness but they are all much sweeter than yams. Make sure that if you want to make a dessert you buy sweet potatoes and not yams . All too often they are sold as one and the same thing, but they are far from being the same vegetable. In the US the FDA's guidelines ensure that sweet potatoes which are yams are labeled as such with yams written underneath, so check the packaging.
You can cook them like potatoes but are especially good baked in their skins like jacket potatoes or steamed. When you boil them they tend to soak up too much water to be good in recipes which call for them to be steeped in fruit juice. When they are cooked, you should remove the skin and use the delightfully colored orange flesh only. Put this in a bowl and squeeze the juice from two King oranges, or Shahi santara as they are called in Urdu and allow the flesh from the potatoes to steep in the juice for about half an hour until some of it is absorbed. This makes for a very different dessert. These oranges are not too sweet, and have a sharp taste; if you use sweeter oranges it may be a good idea to add a little lemon juice. Kinow mandarins are too sweet for this dish.
If you do not particularly like things that are very sweet, steep the potato flesh in imli water (tamarind fruit). This produces a sour-sweet dessert. To make imli water you need 25 grams of the tamarind fruit and a little lemon juice and boil in four cups of water with a pinch of salt until the liquid is reduced to one cup. Then strain the liquid and discard the imli stones. Pour this over the sweet potatoes and leave them to absorb some of the juice.
You can also mash the orange flesh with bananas and maple syrup and sprinkle chopped walnuts over the mixture. If you sprinkle some powdered cinnamon into this it will give you an interesting mouth-watering flavor.
People who are overweight should avoid eating sweet potatoes and stick with yams however. For most people though they have many health benefits, as they help the eyesight and are good for colds, coughs and bronchial diseases.