Hold the body of the shrimp in your dominant hand. Take the thumb of your other hand, slide it under the shell close to where the head used to be, and start peeling it back. Remove all the shells and the legs until you get to the tail.
Starting from the top of the shrimp, gently run the blade of your knife along the back to the tail, but don’t go all the way through.
Spread the two split sides apart to reveal the vein.
take the tip of your knife to lift the vein up, then use your fingers to pull it out. Throw the veins away.