Almost all the crab you see in the grocery store is sold pre-cooked and frozen. This lengthens the shelf-life and preserves the flavour of the meat, but it also makes preparing the crustaceans a simple heat-and-serve kind of deal. To ensure you don’t overcook your precious crab while reheating it, you should use a precision cooker.
It’s not exactly hard to steam or boil crab, but issues can arise if you are prone to distraction, or plan to consume multiples. It takes me about 30 minutes to make it through one Dungeness crab and by that time, the second crab is cold, and I am sad. Similar things happen with a pile of legs. The lower temperature of a precision cooked water bath means you can leave the sea bugs in the bath for a whole hour without overcooking, allowing you to pluck hot crab from the crab bag at your leisure.
Then there is the matter of the bag liquid, which is an added bonus. For most precision cooked projects, sealing your food in a vacuum bag helps it cook evenly and keeps it submerged, but the pointy nature of crab claws and legs makes them a poor candidate for this. Plus, even with vacuum sealing, crab is quite buoyant, so you need a little extra help to keep it submerged.
Rather than fill the base of your bag with butter knives or little weights, you can add a little water (a cup or two) to the bag, then clip it over the side of the bath. The water will keep the bag submerged while becoming infused with delicious crab flavour—it’s essentially crab stock, and you should use it to make risotto. (You can also adds some herbs or Old Bay to the bag, but I prefer my crab cooked plain and dipped in butter.) To make precision-cooked crab, you will need:
Whatever kind of crab you like
Drawn butter for serving
Fill a tub or bucket with water and set it 60 degrees Celsius. Place your whole crab or crab legs in gallon-sized freezer bags, and add two cups of water to each bag. Place the bags in the bath, then clip the open side over the side of the bath. Cook for at least 30 minutes or up to an hour. Remove the crab from the bag, reserve the stock for a later project, and eat with lots of drawn butter.