Potatoes fructose wise are fine, according to food standards http://www.foodstandards.gov.au/consumerinformation/nuttab2010/nuttab2010onlinesearchabledatabase/onlineversion.cfm?&action=search 100g of potatoes have .1g fructose, however 100g of sweet potato have 2.55g fructose.  You can either boil them, toss them in a little oil with salt, pepper and herbs of your choice (rosemary is good) and bake in oven until soft.  You can also cook them in the microwave (just remember to prick them with a fork) until soft.  You can also slice them and fry them in frying pan, heaps of way to cook them.