Van Tran and Anh Vu's summer rolls. Photograph: Felicity Cloake
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'sVietnamese 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 writerUyen 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.