Preheat the oven to 350°F (175°C).
Pat the chicken thighs dry with paper towels and season both sides with 1/2 teaspoon salt and 1/4 teaspoon pepper.
Heat 2 tablespoons olive oil in a large ovenproof braiser or skillet over medium-high heat. Add the chicken and sear until browned on both sides, about 3–4 minutes per side; they will not be cooked through. Transfer the chicken to a plate.
Reduce heat to medium and add the chopped onion to the same pan. Cook until softened, about 5 minutes, scraping up browned bits.
Add the minced garlic, minced ginger, 1 tablespoon ground cumin, and 1 teaspoon Gochujang; stir and cook for 1 minute until fragrant.
Add the 1½ cups rice and cook, stirring, for 2 minutes to lightly toast the grains.
Pour in the 14-ounce can of coconut milk, 2 cups water, 1 teaspoon fish sauce, and 1 teaspoon salt. Stir to combine and bring the mixture to a gentle boil.
Stir in the trimmed, halved green beans, then nestle the seared chicken thighs on top of the rice mixture. Cover with a lid.
Transfer the covered pan to the preheated oven and bake for 20 minutes, or until the rice has absorbed the liquid and is tender and the chicken reaches an internal temperature of 165°F (74°C).
Remove from the oven, let rest 5 minutes, then garnish with chopped cilantro and serve.
