The idea is similar to cooking in a dutch oven or a slow-cooker (which, admittedly, doesn't help my justification cause very much since I already own both of those). Less liquid is needed overall and food cooks slowly until completely tender.
Tagines generally range in size from one quart, perfect for steaming couscous, to four quarts, ideal for Moroccan stews and roasts. Like dutch ovens, tagines can also go from stove-top to oven with ease.
While tagine stews are definitely the most popular and well-known dish to make in a tagine, this dish can be used for much more. Rice, couscous, and beans all do fabulously. With the lid off, a tagine could be used as a roasting dish and then be carried straight to the table. I also wonder if it might be easier to make the no-knead bread in a shallow tagine than the high-sided dutch oven.
In terms of justification, I think it's a matter of deciding how a tagine would fit into your cooking style and the cookware you already have. I've been thinking of buying a smaller dutch oven for casseroles and have also gotten more and more intrigued by clay-pot cooking. For me, buying a mid-sized tagine would satisfy both of those urges, plus my more basic desire to play around with a tagine.
These are a few of the specific tagines I've been thinking about:
Do you own a tagine? What do you cook with it?
(Image: Bram Cookware)