In another pan, like a saute pan, set over medium high heat, heat oil. Add half of the garlic, onion, ginger; cook, stirring often, until soft and fragrant for 5 minutes. Add the chicken thighs; cook, stirring occasionally, until skin begins to brown and fat is rendered, about 10 minutes. Reduce heat to medium heat. Add the rice, stirring often, about 1 minute. Stir in 8 cups of water and fish sauce. Bring to a boil. Reduce heat to medium low. Cook, stirring often, until broth slightly thickens and rice is soft, about 20 minutes. Add white pepper and salt, to taste. Remove from heat. Remove the chicken thighs and place them on a cutting board. Using a small knife and fork, remove and discard the bones and skin, then using a knife, dice the chicken meat. Set aside.