In a 6-qt slow cooker, whisk together the wine, tomato paste, gravy mix, thyme, and 1/2 tsp each salt and pepper. Stir in the shallots. Add the ribs, placing them meatiest side down. Cover and cook until the meat is very tender, on low 8 to 10 hours or on high 5 to 6 hours. With a slotted spoon, transfer the ribs to a plate. Using a ladle or a spoon, skim and discard fat from the sauce. Spoon sauce over the ribs and sprinkle with the parsley, if using.