The humble sandwich doesn't seem like it should be that good. It's just a few ingredients slapped between pieces of bread. It's the stuff of boring school lunchboxes. It's the snack of emergency, got-nothing-else-to-eat nights in.
And yet, done right, a sandwich is a thing of beauty. It can be a taste sensation so delicious that you'll travel halfway across the world just to get your hands on one. You'll dream about this sandwich for weeks afterwards. You'll plan another holiday just to eat another one.
While the definition of a sandwich is pretty loose, for this list I've gone with any meat, cheese or vegetable matter that's encased in bread – bread in any form. And each of these entries is worth the price of a flight alone.
Lobster roll, US
Photo: Eddie Jim
Lobster rolls are a no-brainer: take fresh, delicious lobster meat, smother it in melted butter or mayonnaise (sometimes with chives, or Tabasco, or onion), slap it on a soft, sweet roll, and you have sandwich perfection. Though they're so hot right now around the globe, lobster rolls have long been a staple in the US state of Maine, where you'll find the world's finest.
Where to eat it: Bob's Clam Hut in Kittery, Maine (bobsclamhut.com), is justifiably famous.
Banh mi, Vietnam
You haven't eaten a Vietnamese pork roll until you've eaten one in the town of Hoi An. This is the country's spiritual home of porky goodness, and a stay in Hoi An will spoil your banh mi eating for life: nothing will ever compare. It's the bread, crusty on the outside, soft and fluffy on the inside. It's the fillings, the pickled green papaya, the herbs, the mix of pork cuts, the homemade farmhouse pate. And it's the secret chilli sauce. It is, all things considered, probably the world's best sandwich.
Where to eat it: Madam Khanh – the Banh Mi Queen lives up to her billing, and just pips Banh Mi Phuong as Hoi An's best pork roll.
See also: Where to find the best banh mi in Hoi An
Croque madame, France
Photo: Marcel Aucar
While French cuisine is often associated with such gastronomic wonders as the croissant and steak frites, the Gallic contribution to the sandwich world is just as impressive: the croque madame. Fresh bread is soaked in bechamel sauce, topped with Gruyere cheese and leg ham, before being toasted and topped with a fried egg. Diet food it ain't. But it is delicious.
Where to eat it: Le Petit Cler in Paris (lepetitcler.com) does one of the world's finest.
Bacon butty, England
You don't have to do anything too flashy to achieve perfection. Case in point: the English bacon butty, which at its most basic is just good bread filled with bacon and maybe a little HP sauce. Many have tried to put their own creative spin on the humble bacon butty, but there's little that needs to be done to this sandwich other than devour it.
Where to eat it: Fergus Henderson's St John Bread and Wine (stjohngroup.uk.com) in Spitalfields, London, does the best bacon sanger around.
Vada pav, India
It might not be the dish that immediately springs to mind when you think of India, but this Mumbai specialty – a spiced, fried potato patty smothered in chutney, topped with a fresh chilli and wedged into a small bun – is seriously tasty, and the perfect street food snack. Yes, it's just carbs stuffed into more carbs, but if that's wrong, who wants to be right?
Where to eat it: Aram Vada Pav, near Mumbai's central railway station, is famous throughout the city.
Katsu sando, Japan
The Japanese have an impressive knack for taking other countries' cuisines and making them their own: French pastries in Japan are incredibly good; their adaptation of curry is excellent. And so it goes with the sandwich. The Japanese katsu sando – essentially just a chicken, beef or pork schnitzel on white bread – is simple, beautifully presented, and loved across the country.
Where to eat it: Tokyo's Tonkatsu Maisen (mai-sen.com) is appropriately well known for deep-fried goodness of all persuasions.
See also: Seven dishes you must try in Japan
Photo: William Meppem
It's a toss-up for Portugal's best sandwich: is it the prego, the simple steak sanger; or the Francesinha, the absolute monstrosity of ham, sausage and melted cheese covered in tomato-and-beer gravy; or maybe it's the bifana, a pork roll served with mustard or a spicy, garlicky sauce? I'm going to opt for the bifana for it's pure, simple deliciousness, and the fact you can still walk after finishing one.
Where to eat it: Bifanas vary throughout the country, but Porto's Restaurante O Conga does a pretty mean version.
See also: Food is a key reason to visit Lisbon
Surely the US' greatest contribution to the world of food, the hamburger, has been bastardised the world over by people attempting to improve upon it, but there's still nothing better than a simple, greasy burger patty topped with cheese, maybe a few pickles, ketchup and mustard, and sandwiched in a soft roll.
Where to eat it: You could spend an artery-clogging lifetime searching for the US' best burger, but the Tavern Burger at Loretta's in Seattle (lorettasnorthwesterner.com) is a good place to start.
The name "choripan" is a portmanteau of this sandwich's main ingredients, sausage (chorizo) and bread (pan), and it really is as simple as that. You just need good-quality chorizo, grilled over hot coals, added to a crusty roll with chimichurri or maybe some mustard, and a football game to sit in front of while you eat it.
Where to eat it: Lo de Freddy in San Telmo, Buenos Aires, is the perfect no-frills barbecue joint.
This is Levantine food at its finest, a mix of grilled meat (lamb, or chicken, or beef), tabbouleh, fattoush, tomato and pickled veg, doused in sauce and wrapped in bread. Shawarmas vary across Lebanon, Jordan, Israel and the Palestinian Territories – but they're always cheap and delicious.
Where to eat it: Shawarma Abu-Hani, in the Israeli city of Nazareth, serves its shawarmas on crusty baguettes, with a huge choice of fillings and add-your-own sauces, and they're some of the best around.
What are your favourite sandwiches from around the world? Does Australia have anything to add to the list?
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