In a very large skillet, heat the olive oil until shimmering. Season the pork with salt and pepper and add the chops to the skillet. Cook over moderately high heat, turning once, until lightly browned and nearly cooked through, about 6 minutes. Transfer the pork to a platter, cover loosely and keep warm.
Add the grapes to the skillet and cook until lightly browned, about 3 minutes. Add the shallots and sugar and cook, stirring, until the sugar dissolves, about 1 minute. Add the vinegar and cook until nearly evaporated, about 1 minute. Add the wine and boil over high heat until reduced by half, about 3 minutes. Add the stock and boil until reduced by half, about 4 minutes.
Return the pork and any juices to the skillet and simmer until the chops are just cooked, about 2 minutes. Transfer the pork to plates. Boil the sauce until thick and glossy, about 2 minutes. Stir in the tarragon and pour the sauce over the pork. Serve right away.