Heat the butter in a skillet or large sauce pan over medium heat. Cook the chicken pieces until lightly brown. Remove chicken from skillet and place on a plate.
Add onion to the skillet and cook for about 5 minutes. Add garlic and cook 2 more minutes.
Add the salt and spices and tomatoes. Cook until the tomatoes have released their juices.
Add the carrots, sweet potatoes, lentils, and bone broth. Bring to a boil, reduce heat, and simmer about 20 minutes, covered. Add a little water if needed.
Return the chicken to the skillet. Continue cooking until lentils are soft.