Ask Peter: Poaching prawns
I boil prawns until just cooked for use in salads, etc and am wondering if I should be adding anything to the water to help flavour them? Should I salt the water?
The key to boiling or poaching any seafood (crayfish, chunks of fish, scallops etc), according to my father Bruce, is that they need to be cooked in water as salty as that they came from. In fact, when Dad and his mates would go “crayfishing” down at Ngawi in southern Wairarapa, they’d cook the crays in water straight from the ocean. And I have to say they were the tastiest crayfish I can recall eating. It could also have been because they were the freshest.
So, the answer is yes, salt the water. Last week’s question about “how to make tasty stock” leads on to this subject in many ways, so you should consider the flavour and strength of your poaching liquor. If you simply drop prawns into unsalted water, some of their flavour will inevitably leave the flesh and shell and seep into the water. That’s why the water you tip down the sink after cooking them smells like prawns. If there is some salt in the water, less flavour will seep out.
Too much salt, however, and the prawns will toughen and become salty as the salt “cures” them and makes them too firm. If you add some sliced spring onions, ginger and soy sauce to the water, and less salt, when you boil the prawns they will take on a little of the stock flavour.
The other advantage of this is that you can then put the peelings and heads from the prawns back in the liquid, simmer it for 30 minutes and you’ll have a decent stock. Don’t boil two litres of water to cook a dozen prawns, though, be sensible about how much liquid you need — just enough to submerge them all by 2-3cm. Or you can cook them in several smaller batches, which will give a tastier final prawn.
And don’t overcook them, as prawns can become tough and bland if overcooked — it’s as though all the flavour is squeezed out of them. You can also steam them — adding salt to the steaming liquid has very little effect, but you can add lots of ginger and herbs and boil the liquid for five minutes before you steam the prawns, for a pleasant flavour boost.
My favourite way to cook prawns is to grill them, with heads on, in the shell. Pat them really dry between paper towels and season generously with flaky salt, then brush with a small amount of oil and grill over a high heat until the shells are marked and red on both sides. If the shells are crisp, which this technique will achieve, I eat them shells and all. You can also eat the heads as well — they are delicious if the prawns are super-fresh, or even recently defrosted.
This may seem slightly barbaric but that’s how I have seen people eating them throughout parts of Southeast Asia and I’ve enjoyed them that way too. If you’ve ever made a lobster or crab bisque, you’ll know that you roast or fry the shells over high heat until they become red, then you add aromatic veges and water to make the stock. This grilling does the same thing — it adds much more flavour to the flesh, and the shells become fairly crisp and a real delight to eat. So, if you’re prepared to cook them this way rather than boil them, you might find your prawn cocktail is even tastier!
Related: How to peel prawns
In our Ask Peter series, executive chef Peter Gordon answers your curly culinary questions. If you're stumped over something food-related, send your question to email@example.com and keep checking in for answers. You can read more on Peter on his website, have a read of his Ask Peter articles or check out his recipes here.