Heat 1 Tbsp oil until hot but not smoking in a large oven-safe pan or roasting pan. Place the lamb,
fat-side down into the pan and sear until browned on all sides.
Remove the lamb to a plate and pour off all but 1 Tbsp of drippings. If the drippings are burnt, pour off all of them, wipe out the pan and heat another Tbsp of oil until hot.
Deglaze with the white wine and reduce by half. Place the lamb back in the pot and add the stock, 2 cups of grapes, and the thyme sprigs. The liquid should come to about 1/3 of the lamb.