Step 6: The process of carbonating the strawberries
Add a little water to the pressure cooker with dry ice and strawberries, and seal it up. As the dry ice sublimates (goes from solid to gas), pressure should build up in the pressure cooker, and you will hear it venting. If it vents too quickly, you may want to place it on some styrofoam so it heats up slower. If you loose pressure but it's still very cold, you may want to place it where it's warmer so the ice sublimates faster. If you lose pressure and it's getting warmer, you may need to add more dry ice. We weren't able to keep the pressure up constantly, we just did our best. Whatever you do, don't open a pressure cooker that's still under pressure. This is the tricky part. You will need to tweak and watch the pressure cooker for about 30 minutes (or more, if you can't get the darned thing to lose pressure so you can open it). Make sure your vent doesn't freeze shut during this process. Don't worry, if your fruit freezes, it's still tasty. If the strawberries have frozen, allow them to partially thaw. Serve them immediately so that the carbonation inside of them doesn't have a chance to escape.