Coat a 6-quart crockpot with nonstick cooking spray.
In a large nonstick skillet, warm the olive oil over medium-high heat. Add the carrots and onion; sauté for 4-5 minutes until veggies are tender. Add in the garlic until fragrant, about 20 seconds. Season with the red pepper flakes and a sprinkle of salt and pepper.
Transfer vegetable mixture to the crockpot, along with the dried lentils, broth, kielbasa, and salt. Stir to combine, cover, and cook on low for about 5 & ½ hours until the lentils are tender.
Stir in the herbs and lemon juice. Taste and adjust seasoning, if necessary.
Serve on its own or with some crusty bread, if desired and enjoy!
