How to Make It
Preheat the oven to 375°. Roast 2 of the rosemary sprigs directly on the oven rack for 5 minutes, until charred. Leave the oven on. Strip off the leaves, then finely crush them; discard the stems. In a small bowl, whisk the leaves with the vinegar, mustard and 1/4 cup of the olive oil. Season with salt and pepper.
In a large, deep skillet, heat the remaining 1 tablespoon of oil. Season the chicken with salt and pepper and cook skin side down over moderately high heat, turning once, until well browned, 12 minutes. Transfer to a plate.
Pour off all but 2 tablespoons of fat from the skillet. Stir in the artichokes, tomatoes, caperberries and the remaining rosemary sprigs. Top with the chicken and roast for 15 minutes, until an instant-read thermometer inserted in the chicken registers 165°. Drizzle with the vinaigrette and serve, passing more vinaigrette at the table.