01 - Heat olive oil in a large pot over medium heat. Add the onion, carrots, and celery. Cook for 5 to 7 minutes, stirring occasionally, until the vegetables are softened and the onion is translucent.
02 - Stir in the garlic, ground cumin, smoked paprika, and ground coriander. Cook for about 1 minute, stirring constantly, until deeply fragrant.
03 - Add the rinsed lentils, drained diced tomatoes, vegetable broth, bay leaf, black pepper, and salt. Stir well to combine and bring the mixture to a rolling boil.
04 - Reduce the heat to low and simmer uncovered for 35 to 40 minutes, or until the lentils are fully tender and have absorbed much of the broth's flavor.
05 - Remove and discard the bay leaf. Stir in the fresh lemon juice and taste the soup, adjusting salt and pepper as needed.
06 - For a smoother, creamier consistency, partially blend the soup directly in the pot using an immersion blender, leaving some lentils whole for texture.
07 - Ladle the hot soup into bowls and garnish generously with chopped fresh parsley. Serve alongside crusty bread or over rice if desired.