1. In a large saucepan or Dutch oven, saute ground lamb with garlic cloves until lamb is still a little pink (about 7 minutes) . Add mustard, tomatoes, stir well. Season with salt and pepper.
2. Add lentils, stir well. Add chicken broth and water. Bring to a boil, reduce heat and simmer 30 minutes. Add sweet potatoes, and cook 15 minutes or until potatoes and lentils are tender. Garnish with chopped chives.