In a large soup pot over medium low heat, saute onion in a tablespoon of olive oil or water until softened, about 5 minutes. Add the carrots and celery, and saute until veggies just begin to soften, another 2 minutes. Add the potatoes, garlic, and thyme and saute another minute. Add the water and broth base (or your favorite broth) and bring to a low simmer. Simmer until all the vegetables are tender, about 20 minutes. Stir in the chickpeas to warm. Stir in the parsley and season to taste with salt and pepper, if desired.