How to defrost prawns…and other seafood; and myriad ideas for using prawns

“Buying frozen shell-on coldwater prawns in a catering-sized box and defrosting them ‘to order’, as it were, is really not a bad option. It is, after all, what the fishmonger does.”

Hugh Fearnley-Whittingstall and Nick Fisher, The River Cottage Fish Book

It happens frequently that I get caught on the hoof… suddenly required to conjure up a meal, either for hoards of the hungry; or for the unexpected but elegant.

The solution is to be a wise virgin … or a boy scout.. and to be prepared by keeping a cunningly stocked larder and freezer.

Two of the key ingredients in my culinary backup system are frozen. There are frozen peas… and there are frozen prawns. Both endlessly useful to throw into almost anything, and both more often than not, contrarily, fresher frozen than fresh.

Everything below applies as much to shrimp as to prawns.

Frozen prawns – better frozen than fresh? Really?

Yes, really. Prawns can go off quickly so the sooner they are frozen the better – and that usually means when the fishing ship is still out to sea. The best prawns are those which are frozen individually – so they will be individual in the bag too, rather than feeling as if they are frozen in clumps, these are known as ‘individually quick frozen’ (IQF). You will get the best flavour from raw, frozen, shell-on but head-off prawns.

Cooked prawns (more convenient I admit) are usually cooked at sea by boiling them briefly in sea water, although sometime they’re kept fresh on ice, and then cooked more gently once ashore. Either way the cooking process can make them taste a bit dry and overdone.

Most ‘fresh’ prawns are actually prawns which have been thawed – you can’t know when and how. You are better off being in charge of the defrosting process, and doing it as near to the time of eating as possible.

Why is head-off best?

Most of the prawns digestive enzymes comes from its hepatopancreas, a gland situated just at the base of its head. If the head (or rather the hepatopancreas) is not removed quickly, the enzymes will leach into the flesh, and start to eat away at it… it will become mushy. So the heads should ideally be removed at sea.

Is there any exception to the frozen-is-best rule?

Only if you are lucky enough to find some freshly landed prawns. And if you do, if they still have their heads they will retain more moisture and flavour. But they need to be super-fresh.

prawn and fennel recipe
Unless your fishmonger sources from the daily catch, you may well be better off buying frozen prawns.

Three methods for defrosting prawns safely

The method for defrosting prawns below can also be used for shrimp (which may take less time, unless huddled in a frozen mass); or langouste, cray fish and other seafood.

One: put them in a large sieve under a cold tap, and stir.

Why do you need to stir? Because you don’t want the prawns to stick, frozenly, together.

Why is it important that you use the cold tap and not the hot tap? Because it doesn’t take much for prawns to begin cooking – they are small and delicate. Under a hot tap parts of the surfaces will begin to cook…. Eventually this means that parts will be overcooked and rubbery.

Advantage to this method: dead simple, and the quickest

Disadvantage to this method: you will rinse out some of the flavour

how to defrost prawns
One method is to put in a sieve under the cold tap, and stir.

Two: defrost them in salted water

For this method pour cold water over the prawns to generously cover them, carefully measuring the water as you do so. Then add 1 tablespoon of salt for every 500ml/2 cups of the water, and stir well to dissolve.

Leave until the prawns have defrosted – about 15 minutes. Stir occasionally. Rinse briefly and drain before using.

Salt reduces the freezing point of water. The ice surrounding the prawns will start to melt. This process needs energy – in the form of heat. The heat comes from the surrounding cold water, which is why you need a generous amount of it around the prawns.

Advantage to this method: still pretty simple; the salt adds flavour to the prawns and makes them juicier; the water helps the prawns to defrost evenly.

Disadvantage to this method: slightly more complicated than method 1 – measuring the salt and the water; also takes a bit more time. Take care with adding salt to any subsequent cooking as the prawns will already be salty.

Variations on this method:

There are a couple of other variations on this method:

  • One is to forget the salt but replace the cold water three or four times until the prawns are defrosted.

The advantage of this is that the prawns don’t get too salty!

The disadvantage is that you lose some of the flavour.

  • Another is to make holes in a freezer bag, put the prawns in it, tie it up, and then put the prawns into the cold water.

The advantage of this is that the flavour isn’t able to leech out quite so much.

The disadvantage is that it’s a bit fiddly.

Three: defrosting in the fridge

If you are a chef, this is the method you are most likely to use.

All you have to do is to put the prawns into an airtight container, and put them in the fridge for at least eight hours or overnight. Then rinse and use.

Advantage of this method: also very simple

Disadvantage of this method: you need to be super organised to think ahead sufficiently – one of the best uses of prawns is for emergency, produce-something-incredible-in-an-instant sort of idea – this method is no good for that. Additionally, many domestic fridges don’t have very effective temperature control – they may be set too cool or not cool enough, and different part of the fridge will have different temperatures.

Why defrosting in the microwave is best avoided

Unless you are extremely able and au fait with your microwave it is very easy to overdo things, and start cooking the prawns instead of just defrosting them – they won’t defrost evenly.

Some of the myriad uses of frozen prawns

You can cook defrosted prawns very simply by frying them in garlic, oil, butter, salt and pepper for two or three minutes (less for shrimp), stirring and shaking to ensure they are cooked through.

Below are some other ideas for what to do with prawns:

If you need further tempting, here are some of the images of the recipes outlined above.

  • cucumber and prawn mousse
  • melon prawns and bacon recipe
  • prawn and bacon recipe
  • teppanyaki recipe with chicken and prawns
  • Egyptian shrimp with couscous recipe
  • gambas al ajillo - fried prawns in garlic and gin recipe
  • storecupboard prawns, beans and feta recipe
  • Colcannon with prawns and scallops
  • salad of crispy croutons prawns and marinated feta
  • recipe for tom yum soup
  • best prawn cocktail recipe
  • mango and shrimp salad
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