Heat cooking oil in a medium pan and add the massaman curry paste to it. Cook for a minute and then add the chicken cubes to it.
Cook the chicken for 2-3 minutes. Add coconut milk to it, mix well and cook it covered for 5-10 minutes.
Add the onions, boiled cubed potatoes , cashews and brown sugar to it. The recipe also call for a teaspoon of fish sauce which I have skipped at times, so if you are not big on fish sauce feel free to skip it.
Mix everything together and cook covered for 10 minutes on medium heat. Turn the heat off and the curry is ready to be enjoyed with steamed Jasmine rice.