Quick Vinegar-Braised Chicken with Garlic and Celery Leaves

In a large skillet, heat the oil until shimmering. Season the chicken with salt and pepper; add it to the pan in a single layer. Cook over high heat, turning once, until well browned, 8 minutes. Stir in the garlic and cook over moderate heat just until fragrant, 1 minute. Add most of the celery leaves and stir just until wilted, 30 seconds. Add the stock and vinegar and cook, scraping up any bits from the bottom of the pan, until the sauce is reduced to a few tablespoons, 5 to 6 minutes. Add the parsley and the remaining celery leaves and serve.