In the same saucepan, heat 15 ml (1 tablespoon) of oil. Sauté the ginger, garlic, and spices until the mustard seeds stop bursting. Return the potatoes to the pan. Add the chickpeas and lemon juice. Season with salt and pepper. Remove from the heat. With a potato masher, crush the mixture until smooth. Adjust the seasoning and refrigerate for about 30 minutes.