Tip the chickpeas and their liquid into a small saucepan and add an extra can-full of water. Place over medium heat. Add the teabags, not letting them burst, and bring to a simmer. Cook 5 minutes then take off the heat. Cover and leave to stand 8-24 hours.
Simmer the potatoes in a small pan of salted water until just tender. Drain and leave to cool.
Put the tomato puree, garam masala, cumin and salt into a small bowl. Mix and set aside. Use a mortal and pestle to bash the cardamom pods.
Warm a large saucepan over a medium-high heat and add the oil. Add the bay leaves, crushed cardamom pods, and cinnamon sticks to the pan. Let them crackle for 1 minute, stirring often.
Add the tomato puree mix, stir well for 1 minute, then turn the heat to low and add 150g of the onion-tomato masala. Sauté, stirring often, around 5-7 minutes.
Drain the chickpeas, reserving the cooking liquid. Discard the teabags. Add the chickpeas to the saucepan along with 300ml of their cooking liquid. Bring to a gentle simmer. Add the garam masala, tamarind paste, and lime juice. Simmer 5 minutes, stirring regularly.
Dice the potatoes into chickpea-sized pieces. Add them to the pan. Stir gently, put the lid on and turn off the heat. Set aside to let the potato warm through.