Peel the sweet potatoes and cut them into evenly sized, bite-sized cubes. Measure out 2½ cups.
Rinse the dried green lentils in a colander under cold running water and drain well.
Heat the cooking oil in a Dutch oven over medium heat. Add the frozen mirepoix and minced garlic. Sauté together for approximately 5–7 minutes, stirring occasionally, until the vegetables begin to soften.
1 Tablespoon Cooking Oil, 2 Cups Frozen Mirepoix, 3 Cloves Garlic
Add the diced leftover cooked ham, smoked paprika, ground cumin, and black pepper. Stir for approximately one minute to distribute the seasonings.
2 Cups Leftover Cooked Ham, 1 Teaspoon Smoked Paprika, ¾ Teaspoon Ground Cumin, ½ Teaspoon Black Pepper
Add the rinsed green lentils and cubed sweet potatoes.
1½ Cups Dried Green Lentils, 2½ Cups Sweet Potatoes
Pour in the entire 3 ¾ cups of chicken broth and stir, pushing all the lentils and sweet potato pieces beneath the surface of the broth.
3¾ Cups Chicken Broth
Bring the mixture to a boil, then reduce the heat to a steady simmer. Cover the Dutch oven and cook for approximately 15–20 minutes.
Remove the lid and check the lentils and sweet potatoes for tenderness. Continue simmering uncovered for another 15 minutes, stirring occasionally, to allow some of the excess liquid to evaporate.
When the lentils are approaching tenderness, stir in ⅔ cup of drained diced tomatoes.
Continue simmering for approximately 10–25 minutes, or until the lentils are tender throughout and the sweet potatoes can be easily pierced with a fork.
Check the consistency of the stew. If it becomes too thick before the lentils finish cooking, add a little hot water or additional broth as needed.
Taste the stew before adding any additional salt, since the leftover ham and chicken broth already contribute seasoning. Remove the Dutch oven from the heat and serve hot.