Anchovy, roasted red pepper, potato and egg pintxos

My friend Jose Carlos Capel swings his arm around my shoulder. “Welcome to the tapeo of the future,� he shouts, spraying a mojito into his mouth. From a glass atomizer.

In a compulsively social country like Spain, the tapeo -- the act of shuffling from one tapas bar to the next -- is a ritual of near-religious importance. But tonight’s tapas bash is a different story. We are at a cocktail reception thrown by Ferran Adria, the high priest of avant-garde cooking whose tapitas run to stuff like miniature loaf pans of frozen “air� flavored with Parmesan and gossamer cones filled with trout eggs and soy gelee.

Adria embraces his signature mad-genius part -- speech jumbled, gaze so intense that his eyes seem to pop out of their orbits. Crowding the theatrically dim reception hall of Hotel Ritz are press (Capel is restaurant critic for El Pais, Spain’s largest daily), chefs and sundry members of the city’s beau monde, all gasping and gawking at chefs blowtorching quail eggs in order to enclose them in paper-thin squares of caramel colored with gold powder. Adria’s assistant, enveloped in clouds of hissing-cold vapors, immerses balls of pistachio paste into a caldron of liquid nitrogen. The Martian popsicles emerge frozen on the outside and liquid inside.

I could use a cold beer but settle instead for hot-and-cold daiquiris and a glass of rum “spherified� into beads using calcium chloride, with coconut milk, pineapple juice and a flourish of cotton candy. It’s a pina colada.

Atmospheric dives

Of course, away from Adria’s antics, old-school tapas bars still remain happily true to themselves: heart-stoppingly atmospheric dives with jamones (cured hams) hung from the ceiling, walls plastered with bullfighting photos and crowds shouting orders for another round of batter-fried bacalao. Standbys like ensaladilla rusa (a mayonnaise-drenched potato salad), anchovies and potato tortilla seem inescapable.

But beyond basics, the tapa emerges as a truly protean concept. Place a portion of leftover stew in a miniature cazuela and you’ve got a tapa. Order a cana (small beer), chat up your neighbor, and it’s fiesta. Are you surprised that the Spanish prefer hanging out at bars to entertaining at home?

In its original form, the tapa (the word means lid) was a free slice of cheese or jamon topping a glass of sherry -- to protect the drink from flies and dust. The tradition originated in the 19th century in Andalusia, the center of sherry production, where scorching summers make a full meal unthinkable. Today, defined only by function and size -- a bite to accompany drinks -- tapas vary from bar to bar and from region to region.

Galicia is famous for seafood empanadas, Asturias for chorizo braised in hard cider. Andalusians like to nibble on ethereal fried seafood and marinated potatoes, the Basques on a bacalao-stuffed piquillo peppers. In worldly Madrid, Madrilenos are forsaking the meatballs and patatas bravas (potatoes with spicy-smoky tomato sauce) of the old tiled tabernas and moving on to smart faux-rustic bars serving boutique wines by the glass, fancy cold cuts boards and smoked salmon canapes.

The array of choices is so mind-boggling, at times, that the entire country seems like one vast bar theme park: wine bars and cheese bars, the breakfast bars of Seville and the beer bars of Madrid, bars out of central casting and neo-moderne haunts with tapas artfully arranged in shot glasses, skewers and spoons.

Traditionally tapas functioned as appetite-teasers, but in modern Spain the verb tapear can easily imply eating a full meal. You start with an elaborate canape, move on to a martini glass of new-wave gazpacho sorbet, progress to something neo-traditional, say olive-oil poached clams with Iberian ham, and end with tiny dessert tapas, usually foamy mousses or unusual granitas and ice creams.

In a country where it’s de rigueur for young chefs to collaborate with scientists and where the word deconstruction is uttered in kitchens as routinely as it was at philosopher Jacques Derrida’s seminars, a tapeo can also be a ride on the wild side.

“Today’s tapa has come a long way [from] a morsel that came on or with bread and was eaten out of hand standing up,� Capel, the restaurant critic, explains. “First you dropped the bread, then you started eating tapas sitting down with a knife and fork. Suddenly high-minded chefs are abandoning normal portions in favor of degustation menus of tapas-scaled bites.� It was Adria’s progressions of 30-plus tiny tastes at El Bulli that sparked the small-plates revolution in Spain in the ‘90s. In a culture already hooked on grazing, the trend spread like wildfire. The phenomenon has a name: alta cocina en miniatura, or haute cuisine in miniature.

Designer tapas are all the rage here, in Spain’s most cosmopolitan city, even though its region, Catalonia, doesn’t really have an indigenous tapas tradition. The first salvo was fired a few years ago by Estrella de Plata, a minimalist bar in the once-raffish fisherman’s quarter of Barceloneta. “I couldn’t afford a real restaurant but wanted to do serious food,� says chef-owner Didac Lopez. He did. Soon tout Barcelona was at his doorstep, fighting for a taste of his fried shrimp “lollipops� served with shot glasses of Parmesan veloute.

At Santa Maria, an industrial-chic boite in the edgy El Born district, Catalan cuisine meets the world in tapas like frog legs touched with ginger and soy. At Espai Sucre next door, chef Jordi Burton pushes the envelope further, with five-course tasting menus based only on sweets. I will never forget Burton’s sublime spiced milk pudding with lime peel and toffee and a few baby arugula leaves bridging the gap between sweet and savory.

Whimsical bites

Carles ABELLAN, this city’s star miniaturist, spent nine years at El Bulli with Adria, who always sends clients to Commerc 24, Abellan’s chic, buzzing temple of the nueva tapa. “I couldn’t see making a living cooking intellectual meals that only two diners might understand,� Abellan confesses, somewhat wearily. Instead he applies his own brand of soft-core conceptualism to whimsical bites that reference the vernacular tapas traditions but reconfigure them in new ways. As an homage to the Spanish obsession with gourmet canned seafood, custom-made sardine tins hold raw clams marinated with passion fruit. The ubiquitous mushroom revuleto (scrambled eggs) is also placed in quotation marks: egg foam with truffles spooned into eggshells and nestled in an egg carton. My dessert? A mini bitter chocolate mousse accessorized with peppery olive oil and Maldon salt. It seems utterly Dali-esque, but it actually riffs on a wartime Catalan staple of chocolate-smeared toast eaten with olive oil.

“Young chefs who dream of big restaurants end up opening bars,� says Inaki Gulin, one of the two thirtysomething owners of Cuchara de San Telmo, when I move on to the Basque city of San Sebastian, Spain’s other food capital. Gulin and Alex Montiel, a Basque and a Catalan and both El Bulli alumni, have their own magic formula: restaurant food at bar prices in a narrow, perpetually mobbed space whose most conspicuous decoration is a “Don’t Bush Me� poster.

It’s amazing what one eats here for two bucks. Caramelized foie gras ravioli. Glasses of luxurious chilled crab soup dabbed with tomato marmalade. Stupendous balsamic-glazed pork ribs, slow-cooked, deboned, molded, then flash-grilled in a process that takes two days.

“Barcelona designer bars are elitist and overpriced,� Montiel scoffs. “Ours is a real bar, a populist place where fishermen rub shoulders with Michel Bras and Olivier Roellinger,� he adds, referring to Michelin-starred French heavyweight chefs who take field trips to San Sebastian to see what’s cooking.

In their Basque incarnation, tapas are called pintxos and classically involve bread: baroque canapes decorated with frilly mayonnaise borders, grated eggs sprinkles and colorful pepper confetti, all arrayed on bar counters like edible communion dresses. At Bar Bergara in the affluent Gros district of San Sebastian, so ornate are the pintxos that it takes the owner, Patxi Bergara, and many assistants four hours to assemble the Technicolor counter display. “You should put a ‘Don’t touch’ sign on your pintxos,� I tell Bergara, sad that his Tiffany’s-worthy production will soon be ravaged by hungry mobs. He chuckles and hands me a tartlet with duck gizzards and apples caramelized with Armagnac.

“The pintxo is our most important culinary treasure,� says Juan Mari Arzak, chef-owner of the visionary Michelin three-star restaurant Arzak. He and I are at Alona Berri, a bar near Bergara that pioneered the gourmet pintxo in the ‘80s. The prix fixe small plates degustation here leaves you wondering how it’s possible for a neighborhood joint to serve food that belongs at French Laundry. Like the killingly elegant dish composed of a spoon of grilled eggplant puree, topped by ethereal yogurt mousse, drizzled with aged balsamico and paired on a stark white plate with a shot glass of iridescent-green pea soup.

Arzak eyes a plate of foie gras and candied mango cannelloni. Then he tells me about a dinner he and Adria have just cooked in Madrid for 400 royals who gathered to celebrate the marriage of Prince Felipe, heir to the Spanish throne. I learn that deconstructed jamon sandwiches, rose petal tempura and a mysterious whimsy called Yogurt-Yogurt were among the space-age hors d’oeuvres passed before dinner. And that the cocktail reception had stations where Adria and Arzak demonstrated their latest techniques to stunned monarchs and visiting dignitaries. “Prince Charles, Mandela, Caroline of Monaco -- they couldn’t believe our tapas!� Arzak hoots. So this how the hyper-conservative familia real has chosen to amuse princes and presidents.

Friendly competition

Arzak, who has something of a pintxo addiction, slips away from his restaurant often for a bite and a schmooze. And he’s delighted when local pintxo bar owners dispatch their children for a stage at Arzak to pick up avant-garde tricks.

In Spain, haute cuisine and popular traditions collide, and everyone eats at everyone’s restaurants. No doubt half the young chefs in Spain are busy knocking off Adria’s liquid nitrogen bonbons.

Meanwhile, Ferran Adria is probably at his favorite tapas bar, knocking back canas and nibbling on anchovies and jamon.

Tapeo in your own backyard

Admittedly, the Spanish leave the task of preparing tapas to the bars. But lacking one on your street corner, a tapas fiesta is an easy, jazzy way to entertain, especially on a night too hot for a full meal. In addition to the recipes at left, which take you from soup to dessert, serve good olives, roasted Marcona almonds -- warmed in the oven and tossed with some flaky sea salt -- sliced hard Spanish chorizo or imported salami, and Spanish cheeses accompanied by fresh figs or membrillo (quince paste).

If you can get your hands on Serrano ham, so much the better.

Briny, spicy skewers also make a popular tapa. Try alternating rolled up anchovies, manzanilla olives, squares or red bell pepper and small, slender medium-hot green pickled peppers.

Canapes are another favorite -- especially those with smoked salmon or a spread of Cabrales or Roquefort mashed with a little cream and topped with a few toasted walnuts. And not to forget the ubiquitous Catalan pa amb tomaquet, or tomato bread: slices of grilled or toasted country bread, rubbed with a tomato half and drizzled with olive oil.

To drink? Sherry is a natural, but at many bars in Spain, beer seems to be numero uno, either straight or mixed with a little lemon soda and called clara. Add a dash of Sprite or lemon soda to a glass of cheap red wine on ice and you’ve got tinto de verrano (“summer red�), the beloved summer spritzer of Andalusia. (Sangria is for tourists.) Or go with wine, such as a light Rioja, a Navarra rose, an Albarino or cava. In lieu of my favorite Txacoli (a fresh slightly fizzy Basque white, which, alas, doesn’t travel well) I often serve Portuguese vinho verde with tapas.

-- Anya von Bremzen