Core and Slice the Pineapple (10 minutes): Stand the pineapple upright, exposing the flesh. Center a pineapple corer-slicer over the core. Apply gentle downward pressure while twisting the handle clockwise. Continue until you reach the bottom, being careful not to pierce through the skin. If you do not have a pineapple corer, you can use a knife to cut around the inside of the pineapple, leaving about an inch of the pineapple attached to the outside. Then, cut the core out of the middle, and cut the remaining pineapple into smaller pieces.