are your spot prawns frozen with the heads on? If so you need to remove the heads before the prawns thaw. According to Walcan Seafoods there is an Enzyme that is released from the heads that turns the meat mushy. They suggest just running the heads under water just to slightly thaw and twisting them off. I do that and then let the tails thaw the rest of the way in the fridge.
Since I'm not a fan of the heads anyway, I always remove them from both live and frozen.
I don't like shrimp but I love Spot Prawns. Flavour and texture is totally different. Spot Prawns are sweeter and the texture is more similar lobster or Dungeness crab.
I like them a number of ways including grilled and served with pasta, Garlic Shrimp (Spanish Tapa), stuffed with Dungeness crab, Firecracker Prawns and tonight I plan to make
a Prawn Cocktail with grill prawns and Gazpacho .
https://thibeaultstable.com/2021/06/24/gazpacho-prawn-cocktail/
https://thibeaultstable.com/2012/05/27/prawn-etouffee/
https://thibeaultstable.com/2019/11/04/firecracker-prawns/
https://thibeaultstable.com/2021/02/28/spot-prawns-in-sweet-chili-sauce/
https://thibeaultstable.com/2020/07/25/spanish-tapa-garlic-prawns/
https://thibeaultstable.com/2011/05/07/baked-stuffed-prawns/
https://thibeaultstable.com/2009/05/19/shrimps-prawns-skewered-shrimp-with-lemon-pesto/
https://thibeaultstable.com/2021/03/08/more-of-our-tide-to-table-seafood/