Heat olive oil in a large pot over medium heat. Add the chorizo and cook until browned, about 5 minutes. Remove the chorizo from the pot and set aside.
In the same pot, add the onion, carrots, and celery. Cook until the vegetables are softened, about 5 minutes. Add the garlic and smoked paprika, cooking for another minute until fragrant.
Add the lentils, broth, and bay leaf to the pot. Season with salt and pepper. Bring to a boil, then reduce heat to low and simmer, covered, for 30 minutes, or until the lentils are tender.
Return the chorizo to the pot. Add the kale and simmer for another 10 minutes, or until the kale is wilted and the stew is heated through. Stir in the lemon juice and adjust seasoning with more salt and pepper if needed. Remove the bay leaf before serving.