In a saute pan, brown the ground lamb on medium-high heat for about 5 minutes, breaking it up as it browns. Once cooked, set aside.
In a large soup pot, heat the olive oil on medium heat and saute the onions for 3 minutes before adding in the garlic, celery, and carrots. Saute for about 3-4 more minutes.
Add in the broth, bay leaf, dried lentils, diced tomatoes, and sweet potatoes. Bring to a boil then reduce temperature and bring to a simmer.
Add cooked lamb, drained great northern beans along with sea salt, pepper, red chili flakes, smoked paprika, cumin, thyme, oregano, cinnamon, and allspice and combine. Reduce heat and simmer for 30 minutes.