Wash and clean the chicken, pat dry. Cut into medium strips.
Marinate the chicken with lemon juice, 1/2 tsp garlic paste, 1/2 tsp ginger paste, 1/2 tsp salt, keep aside for 2-3 hours.
Remove the chicken from the marinade, keep aside.
In a bowl take the whipped yogurt, coconut paste, green chilli paste, chili oil, chopped chili pickle, the remaining ginger and garlic paste, salt and mustard oil. Mix well. Add the chicken strips to this marinade, keep aside for another 2-3 hours.
Cut off the central vein of the banana leaves, trim the edges. Warm the leaves over a very low flame, taking care to not char or burn the leaves. (This softens the leaves and keeps them flexible, making the parcels is much easier that way.) Cut the leaves to small pieces.
Take a piece of banana leaf, add a small portion of the chicken to the middle. Top with a little coconut-chilli pickle marinade, finish with a green chilli if you like it hot. Wrap the banana leaf from all four sides to make a parcel, secure with twine.
Gently place the banana leaf parcels in a bamboo steamer, cook on steam for 15-17 minutes.
Serve hot with steamed rice.