Vinegar Marinated Chicken with Buttered Greens and Radishes

Name: Vinegar-Marinated Chicken with Buttered Greens and Radishes
Ingredients: 2 pounds skin-on bone-in chicken thighs; Kosher salt and freshly ground black pepper; ¼ cup plus 1 tablespoon distilled white vinegar; 1 tablespoon vegetable oil; 2 tablespoons unsalted butter; 8 radishes, quartered, halved if small; 1 bunch mustard greens, leaves torn; 4 tablespoons tarragon leaves, divided