In a large pot on medium, heat oil. Add celery, onion and garlic and sauté until tender, 6 to 8 minutes. Add cumin, coriander, turmeric and cayenne and stir until fragrant, about 30 seconds.Add chickpeas and stir. Add broth, salt and black pepper; bring to a boil. Reduce to a simmer; cook for 10 to 15 minutes.Remove 1 to 2 cups soup and purée in an upright blender or in a bowl using an immersion blender. Stir back into pot. (TIP: If using an upright blender, remove plastic stopper in lid and cover with a towel for steam to escape.) Divide among bowls, drizzle with lemon juice and top with herbs.)