Heat olive oil in 5 quart dutch oven, add onion and garlic and give a nice blast of salt and pepper. Cook until onion starts to look translucent. Add sausage and reduce heat. Continue cooking until browned. Add broth, potatoes, lentils and spices, bring to a boil. Reduce heat to simmer, and cover. Allow to simmer until lentils and potatoes are tender, about 1 hour.
Stir in carrot and celery. Add kale to top of soup (do not mix in) and cover, steaming the kale, for about 15 minutes. Stir in kale, add tomatoes and stir. Salt and pepper to taste.