2) Preheat the griddle to high heat. Skewer meat on skewers. Cook over hot coals until done to your liking, about 4 to 5 minutes for medium rare. Place pineapple slices on griddle. Cook on both sides until there are marks and the natural sugars have helped it to brown, about 2 minutes per side. Place beef skewers on top of pineapple slices and garnish with mint.