merguez and sweet potato hash

Weeks ago, I bought some fantastic-looking merguez sausage meat at the farmers' market. (In the winter, when the vegetable stands hold little more than a few sad looking potatoes, I tend to buy a lot of meat and eggs.) Unsure of what I wanted to do with it, I put it in the freezer and promptly forgot about it. Last week, while cleaning out the freezer, I came upon the merguez and moved it to the fridge, determined to make use of it. A couple days later, after taking stock of the rest of the contents of the refrigerator and finding a few sweet potatoes, an onion and some rosemary, it came to me: I'd rustle up a new kind of hash.