In a large pot, sauté the onion and garlic in the oil for about 4 to 5 minutes over medium heat. Add in the celery and sauté for a few minutes more.
Stir in the bay leaf and the spices (cumin, chili powder, coriander, paprika, cayenne).
Stir in the can of tomatoes (including the juice), broth, and lentils. Bring to a boil, reduce heat, and then simmer, uncovered, for about 20 to 25 minutes, until lentils are tender and fluffy.
Stir in kale or spinach and cook until just wilted. Serve and enjoy! The cooled soup can be stored in an air-tight container in the fridge for 3 to 5 days, or you can freeze it in a freezer-safe container (leave 1-inch at the top for expansion) for 1 to 2 months.