How to Make It
In a large soup pot, heat the pure olive oil. Add the quartered yellow onion, carrots and halved celery rib and cook over moderate heat, stirring occasionally, until the vegetables are golden, about 10 minutes. Add the drained chickpeas, the herb sprig bundle and enough water to cover by 2 inches and bring to a boil. Reduce the heat and simmer over moderately low until the chickpeas are tender, about 1 1/2 hours. Add a large pinch of salt and pepper and cook the chickpeas for 10 minutes longer. Remove from the heat and cool for 15 minutes, then drain the chickpeas. Discard the herb sprigs, onion, carrots and celery.
Meanwhile, in a large bowl, soak the red onion in the vinegar for 15 minutes. Drain, discarding the vinegar. Return the onion to the bowl and add the diced celery, lemon zest, lemon juice, garlic, chopped rosemary, oregano and peperoncini. Add the chickpeas and olive oil; season with salt and pepper. Fold in the parsley and serve.