Buying sweet potatoes can get confusing. Sometimes they’re called yams, sometimes there are multiple colors available Here’s what you need to know:  Buy orange sweet potatoes, with firm, unwrinkled skins. In American grocery stores these are sometimes labeled as yams (even though they aren’t). That’s ok, go with it. Avoid white or purple sweet potatoes for this recipe. Those varieties are more starchy and less sweet and won’t give you the same result.  If you’re faced with different varieties of orange sweet potatoes, look for Beauregard, Garnet, and Jewel.