Cut a slit in the back of the shrimp from the tail to top and remove the vein with kitchen shears. Bring a pot of water to boil with a lime cut in half and salt. Drop in the shrimp, turn off the heat and leave sit for 3 minutes covered until the shrimp are no longer translucent. Remove shrimp and place in iced water to stop the cooking process. Peel shrimp. You can leave the shrimp tail on or off, depending on your preference.