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.
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."