In a large wide pot or deep frying pan, heat the oil over medium-high heat. When hot add the onion and stir and fry for about 4 minutes, or until the onion pieces turn brown at the edges. Put un the garlic; stir and fry for another minute. Now add the curry powder and stir once or twice. Quickly add the potatoes, the chickpeas, their reserved liquid, the remaining salt, and enough water to barely cover the potatoes and chickpeas. Bring to a boil. Turn the heat to low, cover, and simmer gently for 30 minutes. Stir in the garam masala and cook another 5 minutes. Serve hot. Enjoy!