Pre-soak the lentils for at least 30 minutes adding equal parts water to the lentils.
In a large cast-iron pot over medium-high heat, add about 2 tablespoons grapeseed oil. Heat 1 minute until hot, add the onion. Season with salt and saute for 3 minutes until soft.
Add the carrots, celery, and garlic and cook for 3 additional minutes. Drain and rinse the lentils then add the lentils to the pot and cook for about 2 minutes. Add the cumin, coriander, and turmeric, stirring for 1 minute. Add the chicken broth and water as well as a large pinch of salt and pepper. Stir, bring to a boil then reduce to low heat and gently simmer for about 10 minutes.
Carefully stir in the diced sweet potato and kale. Cook for another 10-15 minutes, or until the lentils are cooked through but not mushy. Adjust seasoning with salt and pepper. Enjoy with a 1/2 cup of cooked quinoa or by itself.