Preheat your oven to 350 F.
Cut all the vegetables, celery, carrots, and onion into slices and the tomatoes into chunks.
2 medium sticks of celery, 2 medium carrots, 1 medium onion, 14 oz can tomatoes
In a big bowl, mix all the vegetables and the garlic, except for the sweet potatoes, with the ground lamb.
3 medium garlic cloves, 1 ½ pounds ground lamb
Add all the spices, chili powder, cinnamon, cumin, and oregano, as well as salt and pepper to taste the mix and make sure everything is well combined.
2 tablespoon fresh oregano, 1 teaspoon chili powder, 1 teaspoon ground cinnamon, 2 teaspoon ground cumin, Sea salt and freshly ground black pepper to taste
Take an oven-ready dutch-oven type pot and pour the olive oil in it. Place half of the sweet potatoes in a layer on the bottom. Place the lamb mixture on top of the sweet potatoes.
2 large sweet potatoes, 1 tablespoon extra-virgin olive oil
Finish up with another layer of the remaining sweet potatoes.
Place in the oven, uncovered, for 1 hour.