Classic dishes in a tagine use pieced meat...stews, chicken parts, flat roasts (brisket should work, but not a rib roast). As josh noted, the point is to have the savory liquid circulating all around the food.
My favorite is chili. Also working up some beef stews. Sure, the North African seasoning blends are the classic, associated ones, but they're by no means the only ones to consider.
More or less in order of addition to the pan:
3 ounces bacon, cut down and browned
2-3 medium to large chilis...I generally use poblanos and New Mexico long green. Probably about 2 cups. Seeded and coarse chopped.
1 medium onion, diced
(optional) 5-6 mini sweet peppers
salt, pepper, granulated garlic
~ 1/2 cup black, pinto, kidney, or cranberry beans (or white beans with chicken)
1 pound meat*
chili powders to taste...start with a couple teaspoons
2-3 tomatoes, simmered and diced
liquid: beer or wine, ~ 12 oz
Meat: lots of options. At least 90% lean ground beef (note that the bacon fat is left in the pan), chicken, and buffalo. I've been able to get ground venison which is also very lean. The very, very best, IMO, is using a lean, smooth smoked boar sausage.
Beans: I do it by weight, but that's the associated volume. I am diabetic so I have to consider the carbs involved. Work with the amount. Note that more beans may mean adding some water. I DO NOT soak my beans in advance. The caveat is, give the whole batch 5-6 hours to simmer. Smaller beans cook faster, so black beans will be ready before big red kidney beans. I get a batch assembled basically immediately after breakfast, because I'll be noshing from early afternoon through dinner.
Liquids: pale ale with chicken. Beef and buffalo, any good, real beer...not the usual mass-market junk that doesn't have any flavor. German double bock might be my first choice for a little extra richness. Red wine also works surprisingly well; different, but very tasty. Sangiovese, tempranillo, grenache, pinot, merlot...fruity. A tannic cabernet...not so much. Smoked game sausages, a red ale, or an ale with some rye added...an oatmeal stout would work great too.
Chili powders: LOTS of options! Mild tends to be somewhat fruity and less bitter. Medium and hot start using cayenne and paprika. You can also get straight ancho powder; anchos are dried poblanos. If you know your chiles...I'm not picking hot chiles. So I'll use a mix of mild, medium, and ancho.
For more heat, finely dice in hotter chiles. Start with 1 Jalapeno or Fresno and see. You can render the dish too hot to eat by overdoing things, if you don't know the chiles.
Final note: another reason for me to do this right after breakfast is, I'll get my shower *after* everything's assembled. Chiles contain capsaicin, especially in the seeds. Cleaning out the seeds gets it onto your fingers, and it does not wash off easily. I don't use gloves, but that's a very sound precaution. I do, as noted, get my shower right after popping the lid on. The more you want to climb the Scoville scale for the hotter chiles, the more important this is. And if you're getting well up there...use gloves. AND wash your hands *thoroughly* afterwards.