Marinate the chicken in soya sauce, curry powder and lime juice for a minimum 30 minutes to overnight.
Make a fine paste using all the ingredients mentioned for curry paste using a very little water. Keep it aside.
In a heavy wok or pot, heat 1 tsp oil and brown the chicken pieces from sides. (This is optional, I like to do it to get a better texture on the chicken.) Keep it aside.
In the same pot add in the rest of the oil. Add the lemongrass stalk, pandan leaf, wait for 20 seconds. Tip in the curry paste and saute for 10 minutes or till its fragrant.
Tip in the browned chicken, potatoes and curry leaves. Mix well with the curry paste. Stir-fry for 5 minutes, so the chicken is coated well.
Tip in the coconut milk and water and simmer for 10-15 minutes or till the chicken and potatoes are cooked.
Garnish it with coriander and serve hot with rice or roti paratha.