In a large soup pot on medium heat, add water, onion, celery, garlic, salt, pepper, mustard seed, cumin seeds, paprika, oregano, and thyme and stir to combine. Cover and cook for 6–7 minutes, stirring occasionally. Rinse lentils. Add lentils and 21⁄2 cups chickpeas (reserve remaining 1 cup), zucchini or tomatoes, stock, water, and bay leaves and stir to com- bine. Increase heat to bring mixture to a boil. Once boiling, reduce heat to low, cover, and simmer for 20–25 minutes until lentils are completely softened. Remove bay leaves. Stir in 1⁄4 cup lemon juice, then using a hand blender, purée the soup, keeping some texture. Stir in remaining 1 cup chickpeas. Season with additional sea salt, pepper, and lemon juice if desired, and serve.