Season the chicken with salt and pepper and dust lightly with flour. Heat the olive oil in a large, deep skillet. Add the chicken and cook over high heat, turning once, until lightly browned, about 8 minutes. Add the onion and cook over moderate heat, stirring occasionally, until softened, about 4 minutes. Add the wine and simmer until nearly evaporated, about 3 minutes. Add the stock, cover and cook over moderately low heat for 12 minutes. Using tongs, transfer the chicken to a platter.