When you say yam, do you really mean sweet potato, or are you talking about the HUGE yam you get in asian markets?
After responding, I realized I should clarify the difference here as well. It is puzzling why there is so much inconsistency with this terminology. When I wrote Vive, I did some research and found that even between Canada and the US, sweet potatoes and yams are understood differently. My references to yams and sweet potatoes goes with the 'general' understanding of the words. So... when I refer to "yams" in my recipes, I mean the deep orange flesh varieties, either jewel or garnet yam (pictured right) in your grocery stores. Not the whopper yams you may see in Asian markets.
When my recipe calls for sweet potato, I mean the creamy yellowish flesh tuber, pictured left. To double check when shopping, just scrape the flesh slightly to see if the flesh underneath is yellowish or orange.
Now, I'm fairly certain that in the US, the orange-flesh tubers are called sweet potatoes, so this is definitely confusing. Sometimes yams and sweet potatoes can be interchanged, but here is my clarification on the varieties for your reference.
Thanks Patricia for your e-mail and hopefully this will clear up questions for others too!
Cooking Tip: One of my favorite ways to eat yams and sweet potatoes is as "fries". I have recipes in both Vive and TEV for yam fries, and posted a picture with falafels previously, but you can make them simply by peeling, cutting in wedges or slices, tossing with olive oil, sea salt, and then baking for about 45-60 minutes at roughly 400 degrees. Use parchment on your baking sheet for easy clean-up!