Just an update - finally decided to cook the sand prawns in soya sauce (light and dark with garlic and chilli).
What a yummy dish it was! Even TK who does not take prawns enjoyed it!
The texture of the flesh is a cross between that of a crab and a prawn. The cooked flesh is really sweet - that from the body is sweet, firm and juicy while the meat from the claws and legs is more, I am not sure how to describe it, tender and sweet but falls apart in the mouth. Totally different sensations!