Beyond the tarantelo and the octopus salad, the kitchen also does tuna with tomato and fried egg and a Madrid-style callos, tripe stew, a nod to the city the restaurant transplanted itself into. The wider idea, in the restaurant's words, is to reinterpret the recipes of the south with a traveller's eye, dishes born in the Mediterranean that cross through Asia, on a philosophy it sums up as el sabor manda, flavour rules.

Chef José Fuentes started cooking at about 20 under Andrés Madrigal at Balzac in Madrid, and at 23 was running Madrigal's small bistro, Profundo. After travelling and a spell at Sissi, he landed in Zahara de los Atunes in 2008 and opened AlbedriO there with partners Laura López and Jaime Mato, followed four years later by the more informal Trasteo Taberna. The short Cádiz seasons left time to travel and cook in Bali, Peru, Mexico, China and Thailand. After nine years in Cádiz he came home to Madrid and opened KultO at Calle de Ibiza 4, wanting a bar and terrace for informal eating and a room for a long sobremesa. It holds one Sol in the Guía Repsol.

José Fuentes and Laura López opened KultO in December 2015. They had worked together at Sissi in Merano, at Almadraba in Zahara and at Balzac and Profundo in Madrid before becoming a couple in life as well as work, and KultO was the third 'child' after AlbedriO and Trasteo in Zahara. The name is about paying homage, rendir culto, to gastronomy, to Cádiz, to product, to traditional cooking and to enjoyment. Fuentes has joked that his first idea was to open on the island of Ibiza, but the logistics didn't work, and he ended up on Calle Ibiza instead.

They picked this corner of Retiro deliberately, among neighbours like Arzábal, Casa Rafa and Javi Estévez's places, rather than a street where everyone does the same thing. The premises had been a sweet shop, and turning it round was a big job; the decoration was done by Jaime Mato, their long-time partner. The layout stayed through a 2023 refresh of the décor and lighting: a ground floor built around the bar, and upstairs, tables and the terrace.

KultO reinterprets the recipes of the south with a traveller's eye, on a philosophy it sums up as el sabor manda, flavour rules. Fuentes describes himself as a guisandero, a cook of long, slow stews, and his cooking has moved from fusion to a more Mediterranean base built on Spanish recipes, keeping the acid, fresh, spiced and hot counterpoints: mandarin juice or infused Jerez vinegars in place of lime, raw escabeches in place of ceviches. Almadraba red tuna, corvina, borriquete and Retinta beef still arrive weekly from Cádiz, alongside Madrid classics like callos, fried pig's ear and the pepito, and a Del Huerto section that is 90% vegetable, built on seasonal produce and heritage pulses from small growers.

A 2023 rewrite of the carta added the Del Huerto section, with grilled leek with almond, lemon and bottarga and a slowly roasted and smoked chocolate pepper, and a 'Tradición o Morir' section of Mediterranean recipes, such as a Menorca-inspired red-prawn caldereta over panadera potatoes with Ibérico jowl and fried egg, a wok-fried fideuà with baby squid and white prawn, and a garbanzo socarrat with squid alioli. Some things never leave: the pepito, a thin slice of Rubia beef on crystal bread with roasted green pepper and charred habanero, which became a favourite of chefs ordering delivery during lockdown, the Vietnamese-style ssäm of tortillitas de camarones and the extra-crispy pig's ear.

The carta is made for sharing, with many dishes as a half or full ración. Tuna runs through it: a grilled tuna satay (€9.50 each), a creamy Russian salad with almadraba tuna (€9 or €17), tuna tacos with guacamole (€15 or €27), a lightly smoked tuna tartare (€25), tuna with tomato and fried egg (€27), semi-raw tarantelo in a fresh escabeche (€15 or €27) and a spiced tuna bolognese cannelloni (€14 or €23). There's also the KultO pepito (€15), extra-crispy pig's ear with brava (€12 or €21), Joselito chorizo croquettes (€18 for six), grilled leek with seaweed pil-pil, callos a la madrileña (€12 or €21), grilled bay squid with sobrasada meunière (€31), a creamy rice with Ibérico ribs and mushrooms (€27) and a Retinta steak tartare with toasted marrow. The lemon pie (€11) is a house classic.

The wine list runs past 100 references, from all over Spain and beyond, including appellations that fly under the radar. The cocktails were developed with advice from Amarguería and drinks writer François Monti, and the star is the KultO Adonis, served in three versions, with fino, amontillado or oloroso. Desserts include a Turkish coffee in seven textures and the lemon pie with violet meringue and lemon-peel ice cream.

KultO is open Tuesday to Thursday from 12:30 to 00:30 and Friday and Saturday from 12:30 to 02:00, and is closed on Sunday and Monday. Book online through CoverManager from its site, or email reservas@kulto.es. A selection of classics can be ordered for collection or delivery through KultO a Casa.