Begin with the pot roast. Cut into 1-inch-thick slices and tie with kitchen twine into circular shapes. Season the pork in hot oil in the base of a pressure cooker. Add the onion, bay leaf and thyme. Brown for 1 minute, then add juice, cider and balsamic. Cover with lid, lock it and pressure cook for 20 minutes until tender.
Cut buns in half. Lay slices of cheese on the top halves and brown under the broiler until crispy and cheese has melted. Toast the bottom halves, then rub with a garlic clove.
To assemble, lay a slice of the pot roast on the base. Top with Cranberry-Onion Jam and garnish with a fried sage leaf.