
Inspect the lentils for any debris. Bring a small saucepan of water to a boil. Add the lentils and simmer 20 to 25 minutes or until cooked but not falling apart. Drain and set aside.
Meanwhile, heat olive oil over medium-high heat in a Dutch oven or large pot.
Add the sausage and brown well until almost cooked through (will continue to cook in the soup.) Transfer to a paper towel-lined plate.
Return pot to medium heat.
Add the onion and cook 4 to 5 minutes or until beginning to soften.
Add the carrot and celery and continue to cook another 5 minutes or until beginning to soften.
Add the garlic, stir briefly or until fragrant.
Add the beef broth, tomatoes, dried herbs and sausage.
Simmer uncovered 15 minutes. Add the lentils and kale and continue to cook until the vegetables are tender.
Season to taste with salt, black pepper and crushed red pepper.
Turn off the heat and let stand 10-15 minutes.