Like any ingredient, the fresher your shrimp are, the less you have to do. High quality fresh shrimp need little or no treatment. However, this technique is encouraged if you'd like your shrimp to have a fresher taste and crunchier texture, especially for stir-fries.
Place your shrimp into a large mixing bowl, and add sugar, salt and baking soda. Gently massage the ingredients into the shrimp.
Add ice water and ice to the bowl, and stir everything together. Let your shrimp sit for 1-2 hours, or even overnight in the refrigerator.
When you're ready to use the shrimp, run cold water into the bowl, gently stir the shrimp, and pour the water out. Repeat this twice to remove excess salt, sugar and baking soda.