Madrid, Spain: Long taken for granted as a mere bar snack, Spain's humble tapas has graduated from the neighbourhood cafe to the realm of haute cuisine.

Inspired by its simplicity and versatility, top Michelin-starred chefs are taking on the traditional finger-food to whet the appetite, or making a meal of it with tapas-only restaurants.

"Tapas used to be considered something common and almost second-rate," says Angel Moreton, head of the International School of Gastronomy in Valladolid.

"But in recent years there has been a boom and now we are seeing some real marvels."

His school holds an annual tapas competition for visiting chefs from a dozen countries.

The rise of tapas was part of the Spanish food revolution of the late 1990s, driven by legendary Catalan chef Ferran Adria and his prize-winning eatery El Bulli, which closed in 2011.

Adria and his brother Albert opened a tapas restaurant in Barcelona, which still serves El Bulli treats such as tomato tartare, cod with avocado or octopus and squid crisps.

Other chefs have followed their lead in opening bars exclusively for tapas, bringing gourmet nibbles to the street at affordable prices.

"That has been the great revolution in Spanish cooking over recent years," said Moreton. "You find such creativity now even in small neighbourhood bars."

Chicken in kimchi sauce

The word tapa means ‘lid’, and the culinary term is thought to date to the Middle Ages.

Some say it stems from a practice of laying slices of meat over the mouths of cups to keep dust and flies out of the wine.

Others claim an old law obliged drinkers to take a snack with their alcohol to curb drunkenness, and the ‘lids’ were plates of food placed atop wine jars for that purpose.

Either way, to this day tapas are served free with drinks in Spanish bars: often a simple slice of bread topped with ham, cheese, tortilla or whatever else is to hand.

Their versatility encourages creativity, says Sergi Arola, a Spanish chef with two Michelin stars.