Dump the curry paste ingredients into a food processor (or use a mortar and pestle for a more traditional method) and process into a coarse paste.
Pat the chicken thigh fillets with paper towels to remove surface moisture.
Cut the chicken fillets into two-inch cubes.
Peel the potatoes and cut into 1 ½-inch cubes.
Heat the oil in a wide shallow pan (a wok is ideal).
Dump in the curry paste and cook over medium-low heat until the solids begin to separate from the oil.
Spread the chicken on the bottom of the pan and cook without disturbing for a minute.
Stir the chicken and cook, tossing often, just until no longer pink.
Add the potatoes to the chicken.
Drizzle in about two tablespoons fish sauce.
Pour in half of the coconut cream and all of the broth, and stir.
Bring to a gentle boil, lower the heat, cover and simmer for 15 minutes.
Taste the sauce and add more fish sauce, as needed.
Stir in the shrimps, peas and the remaining half of the coconut cream.
Over medium heat, boil gently for five minutes or just until the shrimps are cooked through.
Taste the sauce one last time, and add more fish sauce if needed.