Marinate chicken with light soy sauce and sesame oil for about 2 hours.
In a large pan, fry the onion under medium heat until fragrant. Add the curry paste, chicken and potatoes. Mix well so that the chicken is coated with the curry paste. Pour in 200 ml of water and cover for 10 minutes.
Remove the lid and stir. Add an additional 600-800 ml of water and allow it to boil under high heat.
Once the water starts to boil, add the coconut milk and allow it to simmer under low heat for about 10 minutes. Add salt to taste and turn off heat. Serve.