How to Make It
In a medium enameled cast-iron casserole, heat the oil over moderately high heat. Season the chicken with salt and pepper and add half of it to the casserole skin side down. Cook until browned, 6 to 8 minutes. Flip the chicken and cook until browned on the other side, 6 to 8 minutes more; reduce the heat to moderate if the chicken is getting too dark. Transfer to a plate and repeat with the remaining chicken.
Add the chopped scallions, garlic and kimchi with its juice to the casserole and bring to a boil over moderately high heat. Nestle the chicken in the sauce, cover and simmer over moderately low heat until an instant-read thermometer inserted into a piece of dark meat registers 165° (160° for white meat), 20 to 25 minutes. Garnish with sliced scallions and sesame seeds, if desired, and serve.