Warm the olive oil in a large pot over medium heat. Cook the onion, carrots, and celery for 7 to 8 minutes, until softened.
Add the garlic, cumin, and smoked paprika and stir for 30 seconds.
Add the lentils, diced tomatoes, and vegetable broth. Bring to a boil, reduce to a steady simmer, and cook partially covered for 28 to 32 minutes, until the lentils are tender.
Stir in the spinach and cook for 2 minutes, until wilted. Add the lemon juice, salt, and black pepper.
Ladle into six bowls and finish with chopped parsley.
Notes
Model-authored fallback: the source is a Mediterranean recipe roundup without a complete Recipe JSON-LD card for this dish. The blueprint uses conventional lentil-soup proportions and preserves the source's Mediterranean meal-prep identity.