After at least 12 hours, wash the chickpeas and put them in a saucepan filled with about half a liter of water. Cook over a very low heat. Halfway through cooking time, add the sliced onion, parsley, oil and salt. Stew until the chickpeas are cooked and soften. Serve the soup. If you want to, you can add short pasta pieces to the soup towards the end of cooking time in order to obtain a balanced dish.