To perform the following procedure, you need:
- 1 (or more) live crabs.
- A large pot. Keep in mind that when crabs are threatened, they adopt an "attack posture," where they spread their claws as widely as possible; then they'll grab onto whatever they can. Thus, unless the mouth of your pot is wider than the crab's "clawspan," you may have difficulty getting said crab into it.
- Enough water to cover the crab, plus four or five inches - you want to make sure there will be enough heat energy to swiftly kill the crab when it's dropped in. Fresh seawater is best, but equivalently-salted tapwater will do.
Once you've assembled your ingredients (guess which is the most difficult to obtain?) you can begin.
- First, put the crab into the freezer for a half hour or so. This will put the crab into a dormant, unaware state.
- Once the crab is chilled, put the water in the pot, and bring it to a vigorous boil.
- Take the crab out of the freezer and put it directly into the boiling water. It won't return to consciousness quickly enough to suffer.1
- Return the water to a boil; let the crab cook for 12-15 minutes.
- Remove the crab from the water (careful, it's hot.) Congratulations; the crab is cooked. Now, it's time to clean it. Take it to the sink (or even better, the shoreline) - some mess will be involved.
- Turn the crab over. Using one hand, get ahold of enough legs to ensure that you have a good grip.
- With your other hand: grab the crab's shell, with your four fingers along the front edge, and your thumb on the narrow plate structure on the animal's underside. Now, tear off the shell by pulling hard with your thumb. Important note: remember that the crab was just in some very hot water, and so its entrails will also be very hot. Either allow it to cool a bit first, or be very careful to keep your hand clear of the boiling torrent of goo that will pour out when you rip off the shell. Nothing is unpleasant (or embarassing) like getting a bad burn from crab guts.
- Pour out any remaining liquid, and break the crab in half. You'll now have two sets of legs and a claw, each with the associated structure that attached them to the body. All of the meat is in the legs/claws or these attachment points. Rinse the remainder of the crab's organs off of them.
- Now, pull the gills off of the attachment structures. They're the soft, finger-like streamers2 (which often turn a bright yellow when cooked.)
Excellent! The crab is now ready to eat. Use a crab cracker to break open the exoskeleton of the claws and legs, and a pick to get the meat out of the limbs and leg attachment structures. If you cooked the crab in seawater, it will often be flavorful enough to enjoy on its own (or with some lemon juice or butter.) Still, you might want to mix up some crab sauce for maximum enjoyment.
1The classic method for cooking a crab is to just hurl it directly into the boiling water, which is not good. It's cruel, as it doesn't kill the animal instantly - and crustaceans, when stressed, release a chemical that degrades the quality of the meat. Thus, it's in the best interests of your crab and your character to make sure the animal is thoroughly anaesthetized by the cold first. Another method for dispatching a crab or lobster that's tossed around is to "drown" it in fresh water before cooking it. Crustaceans are very sensitive to saline and pH shifts, so this will definitely be fatal, but it's a lingering and stressful death and is even worse than peremptory boiling. Don't do it. Thanks to sneff for the interesting conversation and authoritative information on this issue!
2BlueDragon says "in the UK we call the gills 'dead man's fingers'. I was told this is because they're poisonous, but it's probably because they look like them." I don't know for sure whether they're poisonous or not, but they certainly look like it!