Heat oil in a large pot over medium heat. Sauté onions, garlic, carrots, and celery until softened.
Add cumin, paprika, salt, and pepper; cook for 1 minute to release the spices’ aroma.
Stir in lentils, tomatoes, and stock. Bring to a boil.
Reduce heat and simmer for 25–30 minutes, stirring occasionally, until lentils are tender.
Adjust seasoning and garnish with fresh parsley or coriander before serving.