Cut the stem off the pepper and clean the insides. Then, cut it in half, strips, or dice it depending on what recipe you'll need them for. Boil a pot of water. Add the bell peppers and cook them (2 minutes for slices and diced peppers, 3 minutes for halves). Transfer the peppers to a bowl of ice water for 3 minutes. Drain them. Put them on a cookie sheet -- making sure the pieces do not touch -- and put it in the freezer until the pieces are frozen solid. Keep in mind, it can take hours for them to freeze completely. Transfer them to a freezer-safe bag and keep it in the back of the freezer. When you want to cook them, thaw slightly then cook.