Japan loves them. And now they're in the UK - strawberries and cream sandwiches

Strawberries and cream – an iconic British combo since the 1800s. But do they belong together in a sandwich?

M&S has rolled out a limited-edition strawberries and cream sandwich, made with strawberries, whipped cream cheese and sweetened bread, which it says is inspired by the "viral Japanese fruit sando". The supermarket chain says it was its top-selling sandwich the two days after its launch.

Strawberry sandwiches are available at some Japanese bakeries in the UK, but M&S's offering appears to be the first time they have been widely available on supermarket shelves.

The idea of serving fruit in a sandwich might sound unusual but it's nothing new in Japan. Known as "furutsu sando", they became popular after Japanese fruit shops opened parlours selling desserts for customers to sample their wares.

They recently became sought-after around the world after going viral on social media, with Western tourists on TikTok scrambling to get their hands on the version sold in Japanese convenience store chain 7-Eleven.

Fruit sandwiches are typically made of sweetened, soft, spongy white bread filled with whipped cream and fruit, typically strawberries or clementine, says Shuko Oda, chef at Koya restaurant in London. They're usually cut into triangles so that the fruit is on display.

"It looks quite pretty," Shuko says, adding that the sandwiches are a "fun play on texture".

Some people in Japan make them at home, but they're more commonly bought from convenience stores, food halls or dedicated fruit sando stores, she says. People often enjoy them as a snack with tea or coffee or served on a plate alongside savoury sandwiches.

In the UK, it's not as uncommon as you might think to pair fruit with slices of bread for a sandwich. Think of banana sandwiches, served with the fruit sliced or mashed, or the nostalgia of childhood jam sandwiches. Coronation chicken sandwiches are made with dried apricots or sultanas, too.

What is a sandwich, at its core? Does it have to be savoury? And does it have to even be made with typical wheat bread - take the jibarito, for example, which is made with fried plantain instead.

What about Scandinavian open sandwiches? And if they count as sandwiches, then what about French toast topped with fruit and sauce?

The Oxford English Dictionary says sandwiches are made of two thin slices of bread, usually buttered, "with a savoury… or other filling".

Though humans have been making bread for thousands of years, the sandwich as we know it today is said to owe its popularity to John Montagu, the fourth Earl of Sandwich. The story goes that he asked his staff to bring him meat between two slices of bread so he could continue playing cards without stopping to eat.

Some of the sandwiches we eat in the UK would raise eyebrows around the world. Take crisp sarnies, coronation chicken sandwiches, or the humble chip butty. But if you're feeling inspired by Japan's strawberry sandos and want to up your sandwich game, here are some more sandwiches from around the world.

Francesinha, a Portuguese sandwich originating in Porto, is a cheese and meat lover's heaven. The impressive structure is made by filling a lightly toasted bread with a steak, sausage, cheese and ham.

More cheese is then placed on top, and the whole sandwich is typically baked in the oven until the cheese melts and then served with an egg on top. A spicy sauce made with Port, beer and tomato is then poured over the whole thing. If that wasn't filling enough already, it's usually served with chips on the side.