This weeks Foodie's-ask question is from Caroline who writes: "Hi Christine: Is there a difference between yam and sweet potato? If there is, which is better to use mashed? Looking forward to your reply." This question can spark quite a bit of controversy as you can witness in this forum thread on the topic of sweet potato versus yams. What is usually marketed in North America as a yam is really not a yam at all, but a sweet potato. I've read a couple of different reasons for this. It might be that the similar look of the African yam and North American sweet potato resulted in the mix up in names when Africans came to North America. I've also read that some marketing boards wanted to distinguish sweet potatoes from regular potatoes, and so used the incorrect moniker for the vegetable. At any rate, the mix up continues to cause confusions - even recipes in reputable cookbooks will call for yams when what they really mean are sweet potatoes. In actuality, a sweet potato and a yam are both eaten as a vegetable but are completely different plants. Despite it's name, a sweet potato is not a potato at all, it is part of the root of a plant and is high in beta carotene. It originated in America but is grown in Polynesia, Asia, and some parts of Europe. It has a smooth skin and is bulbous with tapered ends and is sweet. A sweet potato is what you are used to seeing in the super market and in cans as yams or candied yams.There are a variety of types of sweet potato available that range from yellow, to orange, to reddish orange-coloured skin and flesh. A yam comes from a completely different plant and is a tuber, like a potato. It has rough, scaly skin and is long and cylindrical. It's starchier than a sweet potato with drier flesh and is low in beta carotene. It is grown predominately in Africa, but also in the Carribean, Asia and Mexico. It's harder to find yams at your local market but they are available, especially in specialty stores or markets that carry ethnic foods. Yams are typically white fleshed but can also be yellow and purple fleshed – there are many varieties of yams. They are both a starchy vegetables and are quite often prepared in similar ways. You can bake, boil, fry, mash, etc either. The mashed version that you are thinking of is probably a sweet potato, this is what would be on a Thanksgiving table baked in a casserole dish and covered with marshmallows.

Feel free to ask me any of your food-related questions, just leave a comment on any post in the Foodie-file. I answer one question a week. You will find a lot more answers to cooking questions under the Foodies Ask category of the Foodie-file.