How to Shuck An Oyster
Have the Right Gear
To open—or shuck—an oyster, all you really need is an oyster knife and something (usually a towel or glove) to protect your hand.
I've seen a lot of people shuck oysters using the wrong tools: butter knives, steak knives, screwdrivers, and even a letter opener. Don't be tempted. It will end in stab wounds and tears sooner or later. Oyster knife blades are specifically designed to deal with the toughness of the shells, and the rounded handles gives you more leverage when popping them open.
Knowing how to face the oyster and where to insert the blade. For practical purposes, oysters have top and bottom shells. The top is usually flat and bottoms are cupped. Sometimes oysters can grow in funny wiggly ways, so the distinction may not be as clear. When shucking, the cup side should be down. That's to help preserve the seawater or precious "oyster liquor" when opening.
The hinge of an oyster, where the two shells come together, is where the knife blade is *typically* inserted. I say typically because it's not the only place you can start from. You can also start from the bill or the side, which actually might be easier on some Pacific oysters or Virginicas that tend to break in half on top.
Applying the Right Technique
If you position your knife in the right spot, it doesn't take much force to open the oyster. Wiggle the blade into the hinge until it feels secure. You should be able lift your knife and have the oyster stick to it without moving. Once you get that far, all you need to do is twist the knife like as if you're turning a key or doorknob.
The torquing motion will pop the two shells apart with a nice click. Don't attempt to pry the oyster open -- you might just break your knife that way. Once you get the initial pop, then just pry the oyster open little by little. Run the knife around the side and gradually open it up. Scrape off the top adductor muscle with your blade and discard the top shell.
I personally have trouble getting a clean top shell shuck. Usually bits of the mantle and adductor muscle come off with it. I think it's all in the wrist and angle of the blade. It was actually much easier for me to get a clean cut with the ShuckerPaddy knife. After the top comes off, clear off any shell, grit or dirt from the meat. Then scrape the knife along the bottom shell to dislocate the bottom adductor muscle.
The oyster will have a natural suction against the shell, even once you cut the bottom adductor away. I usually like the nudge the oyster fully away from its shell so that it's completely free and ready to slurp. Another way to get it loose is to rapidly shimmy the oyster in your hand. The vibration usually will cut it loose.
Practice Makes Perfect
Every oyster is unique, which makes shucking a bit of an art form. After a few hundred, you'll get a much better sense of what works best for you.