In a large bowl, mix together ground pork, apple, onion, garlic, teriyaki sauce, and egg. If too dry, add some juice from the can of pineapple slices. Form into eight patties.
Lightly oil grill grate. Grill pork burgers for 10 minutes, or until well done. Toast buns on grill. Serve burgers on toasted buns topped with pineapple slices.
