Add ground black pepper and fish sauce. Cook for 30 seconds.
Pour-in coconut milk. Let boil and reduce to half. Note: this is done by letting coconut milk evaporate by boiling in medium heat in about 20 to 25 minutes.
Put-in shrimps. Cook for 5 to 7 minutes.
Add green and red chilies. Cook for 5 minutes.
Turn-off heat and then transfer to a serving plate