First, a consideration on prawns/shrimps and whether you should buy them fresh or frozen. I say this because prawns are an exception to the general rule that we should always buy fresh ingredients and the difference between fresh and frozen ones is not so big. Furthermore, most of the prawns you buy is frozen at sea and shipped to us because fresh shrimp has a very short shelf-life. When you buy it ‘fresh’, unless you know the fishmonger and can trust what he says, it is likely to be defrosted (maybe even a couple of days before), rather than fresh. Therefore I suggest that you buy the frozen ones and defrost them just before use.
Unless, like I said, you can source the fresh ones from a trusted supplier. Do not buy precooked ones!
If using frozen prawns, you can defrost them quickly placing them in a bowl filled with cold water. Some suggest putting them in a bowl under running water, allowing overflowing as it is faster.
A second consideration is whole shrimps vs tails. In the UK you will mainly find prawn tails. They are quicker and easier to use, but don’t have much flavour. Back home (I’m from Sardinia), prawns are normally cooked whole and the head is actually considered the part with most flavour, and rightly so; I remember making a dish once, back home, using only the tails and being told off because I had discarded the heads; since that person definitely had a point, I took that complaint very seriously and started to think how I could keep the flavour without forcing my guest to shell their prawns as they are eating (which can be quite awkward).
This is why I started making a stock with the heads and shells and adding it to the dish, in order to offer the practicality of serving the tails but keeping the flavour of the whole thing
This is how to shell the prawns (obviously you will need to defrost them as above if using frozen ones):
- Remove the head
- Remove the shell, leaving only the last bit as it will look nice in your presentation
- Using a sharp knife, make a shallow cut at the back of the tail and extract the vein (usually it’s black, it might be transparent)
- Cover and chill until ready to use
NOTE: what the recipes usually call ‘vein’ is actually the intestine of the prawn; it’s not harmful to eat, but it might be a bit gritty. Furthermore, that incision, when the tail is cooked, will create a nice ‘butterflied’ look
Now let’s make the stock with the heads and shells; a prawns stock can be made in many different ways (and you will find many different recipes), but I find that this process gives a better taste and texture.
NOTE: I’m indicating 1/2 litre of water for 12 large or 16 medium prawns, you can make a proportion based on how many prawns you are cooking:
1) Heat 1 tablespoon of olive or rapeseed oil in a pan
2) Add the prawns shells and heads and cook until they turn red
3) Add 1/2 litre of water, bring to the boil, add 1 tbsp. tomato paste and 1 tsp. anchovy paste
4) Simmer for 15 minutes, skimming the surface
5) Take the pan with the shells off the fire, and blend (using a hand blender)
6) Passing it through a fine sieve lined with muslin, transfer to a clean pan or any suitable container if not using immediately
A consideration on seasoning: I have not forgotten the salt, but I will normally use thiis stock for other preparations, and it’s likely to be reduced further depending on what I’m doing, so the salt should be added whilst preparing the final dish.