Heat 1 tbsp sesame oil in a large frypan over high heat. Add the pork and cook for 2-3 minutes, tossing until lightly browned, but not cooked through. Set aside on a plate and reserve pan on heat. Add the broccoli, capsicum, and bok choy stalks and cook for 3 minutes. Add the sauce and cook for 1 minute, until slightly reduced. Then add 225 g pineapple pieces, bok choy leaves, pork and any resting juices back to the pan and cook, tossing, for 1-2 minutes, or until the leaves are wilted.