Saute garlic, cardamom and cloves in hot oil in a deep heavy-bottomed pan till fragrant. Add in onions and cook till tender and translucent.
Add in spices and fry for a few seconds before adding in the chicken and potatoes. Stir-fry carefully to evenly coat with spices.
Add in the beans, tomatoes, coconut milk and lemongrass. Season with salt and pepper. Cover and let it simmer for 15-20 minutes till chicken and potatoes cook through and become tender.
Stir occasionally in between, adding water if necessary to get desired consistency. Once done, garnish with chopped coriander leaves and serve warm over a bed of rice or with a side of thick crusty bread.