Beyond the anchovies and the red tuna tartare, the raw bar runs to oysters aliñadas with cucumber dashi, smoked almond and roasted tomato, tiger mussels the menu itself calls 'the Madrid version of a sea croquette,' and an aged sea bass served cold, Bilbao style.

El Señor Martín began in 2008 as two fishmongers in the Chamberí and Chamartín markets, founded by Javier Rodríguez Tur, an economist and brand-communications expert from Cádiz who left everything to go into food. The Chamberí fishmonger, designed in black to make the fish shine, won the INNOVA prize for the best shop in the Community of Madrid and AECOC's award for the most innovative fishmonger. In 2012 it joined the Mercado de San Miguel, where it still runs three fish stalls, with Andalusian-style fried fish, and a first restaurant on Calle Mayor, inspired by the smarter beach chiringuitos of the south coast, came before the current one. The restaurant on Calle General Castaños opened in summer 2018, aiming to be a sanctuary for fish lovers, and its opening carta named each fish by its port: dressed borriquete from Algeciras, white prawn from the Alborán Sea, Huelva carabinero, Barbate red mullet, urta from Conil and striped prawns from Sanlúcar. It was named Madrid's Best Traditional Restaurant by the Guía Metrópoli in its first year, is recommended in the Michelin Guide, and won a Repsol Sol in 2023.

Señor Martín is a fish: the John Dory, known in Cádiz as gallopedro, in the Basque Country as muxu martín, in Catalonia as gall de Sant Pere and in Galicia as martiño or sanmartiño. The names come from the saints' calendar. Legend has it that Saint Peter lifted the fish from the water and left his fingerprint on its flank, and 11 November, Saint Martin's day, is said to be the best day to catch and eat it.

Every piece of fish and shellfish is chosen daily after talking to fishermen, producers and the house's scouts at the market of origin: freshly caught, arriving within hours, from small-scale inshore fishing on the Spanish coasts, including lesser-known species alongside the classics. The kitchen respects closed seasons and biological cycles and argues for minimal intervention, with the grill its favourite tool, alongside steaming, charcoal, stews, frying, pickling and raw preparations. Whole pieces, such as sargo real, bocinegro or John Dory, are shown at the display and priced by weight.

The carta runs from Bakio anchovies cured in the house (€30 a portion) and oysters natural or dressed with cucumber dashi to tiger mussels, 'the Madrid take on a seafood croquette', a cod-tripe Bikini, Iranian Osetra caviar, wild almadraba bluefin tuna tartare, Huelva scarlet shrimp Russian salad and aged sea bass with cold Bilbao-style sauce. Desserts include a brioche torrija with merengada ice cream.

Through its Hermanos de Mar series, El Señor Martín opens its kitchen to chefs who share its view of the sea: Abel Álvarez of Güeyu Mar in April 2021, Pablo Sánchez of Los Marinos José in April 2022, David de Coca of Sa Llagosta in November 2022, and Pepe Solla of Casa Solla with Roberto Rodríguez of Artesanos de Pesca in January 2024.

The restaurant is split over two floors. The street level, with tables and a gastronomic bar by the open kitchen, is the most social; downstairs is quieter, with a main room and a private dining room. Open Tuesday to Saturday from 13:30 to 23:00, with the kitchen serving from 13:30 to 16:00 and 20:30 to 23:00; closed Sunday and Monday. Book online by floor through its site, call 91 795 7170, or email reservas@srmartin.es.