I'd like to make a sushi roll or a vietnamese prawn roll but can't seem to get the prawns to straighten, which would make them much easier to roll up. They were still curled up after I cleaned them before the boil.
- Wash the shrimp and remove only the head.
- Insert a bamboo skewer along the shrimp from head to tail, running along the legs without touching flesh
- Drop into boiling, salted water for 3-5 minutes (do not put a lid on); after this period, they'll change color and rise to the top. If they feel firm, they are cooked.
- Quickly place them into ice water, which helps them have good color and stops the flesh from shrinking and becoming hard.
- When shrimp are cold, remove from ice water and drain in a colander.
- To remove the skewer, use a screwing motion.
- Remove shell from around body, but not the tail.
- Butterfly cut open, cutting from head to tail along the belly with the knife only going halfway in.
- Use the knife or your fingers to open it up and flatten it carefully, without further breaking the flesh.
- Remove vein and rinse with lightly salted water. Lay on papertowels to drain.
If using for sushi rolls, remove tail and cut in half lengthwise.
I saw on America's Test Kitchen that if you make small slices on the underside of the shrimp, you can reduce the amount of curling. They say "To prevent the batter from clumping on the inside curl of the shrimp, we made two shallow cuts on the underside of its flesh."
Their recipe page has a video, but you need an account to view it. This recipe is for shrimp tempura, but the technique should work for any kind of shrimp dish.
They're using "colossal" shrimp (8-12 per pound). The chef says "there's a very easy solution here. You just take the shrimp and roll it right over so it's belly up, and you make two little cuts—about a quarter inch deep cuts and about an inch apart. These are little release cuts and they're going to prevent the shrimp from curling up as much."