Soak the chick peas overnight in plenty of cold water or use ready cooked - canned chick peas. Rinse several times and drain well.
Place the chick peas, water and ginger in a large saucepan over a high heat, bring to the boil, cover the pan and simmer for 1-1 1/2 hours or until the chick peas are tender.
Add the potato, cumin, turmeric, chilli powder and green chillies and mint, if you are using dried. Return to the boil, cover the pan and simmer for a further 15-20 minutes, until the potatoes are tender.
Melt the ghee over a medium heat and fry the oinion until they are lightly browned. Stir them into chick peas with salt and garam masala powder.
Remove the pan from the heat and stir in the lemon juice and fresh mint.