Heat a pot or dutch oven over medium-high heat. Add sausage and cook for about 5-7 minutes until browned. Flip and brown the other side. Transfer to a plate, and set aside.
Add diced onions, carrots, and celery to the pot. Sauté veggies until softened for about 5 minutes. Stir in jalapeño and garlic, and sauté for 1 minute. Add salt, chicken broth, lentils, and bay leaf. Stir well. Bring to a boil, reduce heat to simmer, and simmer for 30 minutes.
When almost all of the liquid has absorbed and the lentils are softened, stir in kale & reserved sausage. Cook for about 5 minutes until kale wilts and the liquid has been mostly absorbed. Remove bay leaf and stir in lemon juice. Serve with parsley and extra lemon if desired.