Heat oil in a large pot over medium-low heat. Add onion and cook until fragrant and softened, about 3 minutes.

Add chicken pieces and curry paste. Sauté for 3 to 5 minutes, stirring to coat everything in the paste. Add halved potatoes and stir to combine.

Pour in coconut cream and 1/2 cup water or broth. Season with salt. Bring to a simmer and cook for 20 to 30 minutes until potatoes are fully cooked and tender, adding more liquid as needed for desired sauce consistency.

While the curry simmers, cook jasmine rice according to package directions.

Stir in fish sauce and brown sugar to taste. Serve the curry over rice, topped with fresh chopped cilantro.