To make the black pepper prawns heat half the sunflower oil in a wok over a high heat.
Add half the prawns and stir fry quickly for about a minute then add half the curry leaves and fry for about 30 seconds and then remove to a separate plate. Repeat the process with the remaining prawns. They should be half cooked at this stage.
Wipe the wok clean and return to the heat. Add the butter and melt until foaming. Add the garlic purée, ginger purée and spring onions and fry until aromatic (about 2-3 minutes) then add the chilli paste, miso paste and cracked black pepper and fry for a further minute.
Add the sauces and chicken stock and bring to the boil and reduce by ¼. Combine the corn flour and water to make a thin paste and whisk into the boiling sauce and thicken. Then add the prawns and curry leaves to the sauce. Place into a large bowl and serve with the rice and iceberg lettuce cups.