Fillings vary, incorporating prawn, chicken and pork, but the basic aim is to cram as much fresh stuff into some rice paper as possible. If you haven't tried them, you're in for an absolute treat.
If you're not familiar with these little delicacies - also known as fresh spring rolls - then my, you've got a treat in store. Cucumber granita aside, they're just about the freshest thing I can imagine: a jumble of crunchy raw vegetables, soft, aromatic leaves and cool, squidgy noodles, all stuffed snugly into a featherlight rice wrapper.
In fact, summer rolls were what first hooked me on the fresh flavours of Vietnamese cooking: so much lighter and punchier than the fried snacks I was expecting. Gourmet magazine's description - "a salad packed into an edible container" - sums them up nicely.
Once you've mastered the basics, you can play around with the recipe to your heart's content (and it ought to be content: many versions are very low in fat) - but the guiding principle should always be to cram as many contrasts of flavour and texture into each bite as possible, while retaining the roll's elegant appearance (ie don't get too Man v Food about it). But what's the best way to start?
Rick Stein notes there are endless combinations of filling, but the most popular version online seems to be a prawn roll, with or without pork. Most recipes simply specify cooked prawns, but Van Tran and Anh Vu's Vietnamese Market Cookbook briefly simmers them in lemongrass-infused coconut milk before use. The lemongrass is a nice touch, but I can't taste the coconut - it's more important, I think, to buy the prawns raw and poach them in salted water, as Vietnamese food writer Uyen Luu suggests, so they act as the savoury element in what's otherwise a fairly sweet dish. Prawns in Vietnam tend to be big spiny monsters that are halfway to langoustine, but there's no reason you shouldn't use smaller north Atlantic prawns if you'd prefer - although the large, vibrantly coloured exotic versions do look prettier in the wrappers.
A number of the recipes also suggest adding pork, usually belly - cooked, as Luu and Stein suggest, by simmering the meat in salted water until tender, then thinly sliced before use. As well as making the dish more substantial, the meat, like the prawns, acts as a savoury balance to the other ingredients, while also adding a richness of its own. For a lighter dish, though, I'd leave it out.
(If you eat neither pork or prawns, Rosemary Brissenden's recipe in South East Asian Food suggests chicken thigh as an alternative, or you can find plenty of vegetarian versions online, including the Gourmet recipe referenced here.)
Lettuce - the soft sort rather than crispy iceberg - seems to be the one constant in summer rolls, and the leaves are usually used whole as a layer in themselves, although Brissenden calls for them to be shredded before use, which I think gives the rolls a better texture. Gourmet, however, uses chinese cabbage instead, which I'm not keen on: it may be crunchier, but the slightly sulphurous flavour seems all wrong. Luu stops with lettuce, but most people stuff in a few more vegetables: Stein and Brissenden go for beansprouts, Tran and Vu shredded carrot, cucumber and, rather surprisingly, pineapple, and Gourmet carrots. Of course, Gourmet's aren't just any carrots - they're tossed with lime juice and sugar before use, which makes the filling a bit mushy. It also spoils the intended contrast between the slightly bland, crunchy roll and the punchy dipping sauce. Pineapple isn't too my taste either - too sweet - but otherwise I'm keen to pack in as many different textures and flavours as possible, with the exception of beansprouts, which, though pleasingly crunchy, don't taste fresh enough for my liking.
Herbs play a big part in Vietnamese cooking - they're often used more like a salad leaf than a garnish, and in the summer roll it's no exception. Tran and Vu keep things simple with just coriander, but everyone else goes a bit crazy. Garlic and chinese chives (which you may remember from our old friend pad thai) are popular - used by Brissenden, Stein and Luu - as is mint (Brissenden, Luu, Stein and Gourmet). Stein also goes for thai basil, while Luu suggests also adding cockscomb mint, perilla leaves and coriander, describing cockscomb mint as resembling "minty lemon balm" and perilla leaves as having "peppery, cinnamon and fennel flavours". They take a little tracking down, cycling around London on the hottest day of the year, but I'm pleased I've done it: the perilla leaves especially add a really unusual, sweetly spicy taste to the rolls. If you can't get them but have a big supermarket nearby then thai basil is a nice substitute, and works well with the slight soapiness of coriander and the freshness of mint. Don't be tempted to substitute Italian basil if you can't get either though; just leave it out.
The only bulky element of this delicate dish - although rice vermicelli aren't exactly pappardelle, they are surprisingly difficult to get absolutely right (again, see pad thai). The ideal texture, as far as I can tell, is yielding but still slightly chewy. Many recipes dodge the issue by pointing you towards "packet instructions", but Stein suggests dunking them in boiling water for two minutes, while Luu goes for 5-10 minutes, "until soft". I find Luu's a bit too squidgy and Stein's a little al dente - about four minutes seems ideal. All the recipes are careful to remind you to rinse the noodles, to stop them cooking any further, and then to drain them thoroughly before use, or you'll end up with soggy summer rolls, which would be a sad thing indeed. Gourmet, which I'm beginning to suspect of wilful non-conformity, instead uses rice sticks of the flat, wide kind normally seen in dishes such as pad thai, soaked for 10 minutes and then tossed with lime juice before use. Again, I don't think the filling needs any extra liquid or indeed flavour - that's what the dipping sauce is for - and the noodles themselves are too bulky for easy rolling.
Rice paper rounds are used to wrap up the filling ingredients, but this needs treating with some care; it must be soft enough to roll, but not so soft that it tears in the process. I encounter a variety of wisdom intended to help me achieve this. Brissenden suggests dunking them in warm water and then rubbing them with wet hands until "there are no longer any brittle patches". Gourmet is also in the hot water camp, suggesting leaving them in for 15-20 seconds "until soft and pliable" and Tran and Vu just pat them with wet fingers, although, in a note underneath, they go on to say they finally figured out that "the simplest way to prepare the rice paper is to submerge it in boiling-hot water before rolling. This makes it very soft and easy to work with, and the water evaporates quickly so that the rice paper is not soaked." I try out both methods in the interests of fairness, and discover it's quite fiddly to test the softness of rice paper in boiling water. The patting method works much better, but it's far easier to do as Stein and Luu do and simply dunk the rounds in cold water. Stein leaves them to soak for one minute, and Luu whips them straight out again - but I find these far too brittle to roll. I won't give an exact time, but instead of leaving them to soak, I'd pat them in the water until they feel pliable: this is easy after a couple of goes, and rice paper is so cheap it doesn't matter if you make a few mistakes along the way.
Brissenden and Gourmet both add roasted peanuts, which I like - they add a burst of both texture and salt to the rolls. Gourmet also adds a spice - chilli is usually confined to the dipping sauce, but they use it in the filling too, unnecessarily as far as I'm concerned.
This is probably the trickiest aspect of summer rolls, but a little practice makes perfect. Tran and Vu offer some useful advice that Gourmet should heed: "Put less filling on the rice paper than you think you'll need." Otherwise, it's hard to seal the rolls (and the same goes for burritos, stuffed vine leaves and all manner of wraps). They start their rolls with a pile of noodles, but visually it's nicer to see some pink prawn and green herbs through the translucent wrapper. Brissenden, Tran and Vu all do two layers of filling, folding the rice paper over one lot before adding the next, while everyone else constructs it more like an envelope, folding the sides in and then rolling the paper up tightly around the filling - an approach I find easier to manage.
There doesn't seem to be one standard dipping sauce for summer rolls. Tran and Vu make a classic sweet, sour and savoury number from sugar, water, fish sauce and lime juice, flavoured with bird's eye chilli and garlic, and Stein's is very similar but without the water, and with added ginger. Brissenden adds rice vinegar and shredded carrot. I'm not keen on the vinegar, on the basis that lime juice should be sour enough, and as I'm including shredded carrot in my rolls there's no point having it here.
Both Luu and Gourmet do something quite different. Luu's sauce starts with fried garlic and adds hoisin, vinegar, chilli sauce and water, garnished with crushed peanuts, while Gourmet's is a blend of hoisin, peanut butter, water, lime juice and soy sauce, whisked together until smooth. Both delicious, but I find them too cloying and heavy: I'm after something lighter and zingier to match the freshness of the rolls themselves. A simpler mix of lime juice, chilli, sugar and fish sauce fits the bill perfectly.
Perfect summer rolls
150g pork belly, rind removed (optional)
8 large raw, peeled prawns
1 stalk of lemongrass, crushed
1 block of rice vermicelli
4 sprigs of mint, leaves picked
4 sprigs of coriander
4 sprigs of perilla leaves or thai basil leaves (optional)
2 chinese chives, cut into 10cm lengths (optional)
1 carrot, peeled and grated
¼ cucumber, cut into thin matchsticks
1 soft lettuce, ½ shredded
4 tbsp salted roasted peanuts, roughly chopped
8 rice paper wrappers
For the dipping sauce:
1 tbsp sugar
2 tbsp lime juice
1 tbsp fish sauce
1 garlic clove, crushed
1 bird's eye chilli, finely sliced
Put the pork belly in a pan and cover with water. Add 1 tbsp salt and bring to the boil, then turn down the heat, cover and simmer for about 20-25 minutes, until cooked through. Allow to cool.
Bring a small pan of water, with the lemongrass and 1 tbsp salt added, to the boil. Add the prawns, turn down the heat and poach for two minutes until pink. Drain and cut in half.
Put the noodles in a large bowl and pour over boiling water. Add ½ tsp salt, leave for about four minutes until al dente, then rinse well in cold water and drain thoroughly.
Set out all the ingredients within easy reach of a clean, dry chopping board. Half fill a bowl big enough to fit the wrappers in with cold water, and then dunk one in and keep patting until it's pliable, but not completely soft. Lay flat on the chopping board.
Arrange two crossed chives, if using, horizontally towards the bottom edge of the wrapper. Top with four prawn halves in a horizontal line, and top these with a line of herb leaves. Add a pinch of carrot and a few cucumber sticks, then a small clump of rice vermicelli. Finish with some shredded lettuce and a line of crushed peanuts.
Bring the bottom edge of the wrapper tightly up over the filling, and then fold the sides in over it. Continue to roll up tightly and place on a plate, join-side down. Cover rolls with lettuce leaves to keep them fresh.
Once all the rolls are made, make the sauce. Whisk the sugar into the lime juice to dissolve, then add the remaining ingredients. Adjust to taste if necessary.
Summer rolls - better than spring rolls or just a poor relation? What do you put in yours? And your advice please: what other Vietnamese delicacies should I be looking out for when I go in September?
Felicity Cloake's perfect Vietnamese summer rolls. Photograph: Felicity Cloake