I found the original recipe for this soup on Kalyn's Kitchen. It was a good fall soup. The recipe with my modifications are below. All measurements are approximate.
8 oz. lb. raw chicken or turkey sausage links (preferably spicy)
1/3 cup chopped celery
1/3 cup chopped onion
2 tsp. olive oil
4 cups chicken stock
1/2 cup brown lentils
1 tsp dried sage
1/4 tsp. dried thyme
1 can diced tomatoes
1 medium sweet potato diced (bite size diced)
salt and fresh ground black pepper to taste
Heat olive oil or just cooking spray in heavy soup pot, then saute celery and onions for about 5 minutes. Add chicken stock, lentils, sage, thyme, and a bit of fresh ground black pepper, and simmer for 20-30 minutes.
While soup is simmering, cut sausage lengthwise and then into slices. Cook in a skillet until browned. Remove from skillet onto paper towels to drain.
After 30 minutes, add canned tomatoes, chopped sweet potatoes, and cut sausage pieces and cook at a very low simmer about 30-60 minutes more (until sweet potatoes are tender). Season soup with salt and fresh ground black pepper and serve hot.