de_DEDinner by Heston Blumenthal is a notable fine-dining destination located in Central London near the Knightsbridge tube station, situated in the district of the same name within the Mandarin Oriental Hyde Park. Opened in January 2011 to replace a previous restaurant, the establishment was created by Heston Blumenthal and initially headed by Ashley Palmer-Watts, who had previously served as the head chef at Blumenthal's restaurant The Fat Duck. Palmer-Watts was later succeeded by Jon Miles-Bowring, followed by Adam Tooby-Desmond. Blumenthal and Palmer-Watts originally developed the concept by researching historical menu choices with the assistance of a food historian and curator at the British Library, drawing inspiration from British dishes dating from the fourteenth century and beyond. The restaurant's name signifies the main meal of the day regardless of when it is consumed, and it serves both lunch and dinner.
The culinary style focuses on items based on historical British recipes, with each menu item including details such as the year of its origin. Examples of featured fare include a scallop dish dating from 1826 published in The Cook and Housewife's Manual, alongside scallops and peas with cucumber ketchup, a bergamot-cured mackerel salad, and a clockwork spitroast used to cook pineapples for a dessert. Particular acclaim has centered on the Meat Fruit, a chicken liver mousse meticulously crafted to resemble a textured mandarin orange. Diners can also experience a hand-cranked ice cream trolley that utilizes liquid nitrogen to mix custard tableside.
The interior was designed by Adam Tihany and features full-length windows that offer a direct view into the kitchen, alongside a pulley system inspired by a sixteenth-century design utilized for the British Royal Court. Brand identity items, including the menus and logo, were created by the design agency Seymourpowell. The dining room accommodates up to 110 guests under a comfortable dress code, and reservations are required. Following its London launch, the concept expanded internationally with the opening of franchises in Melbourne, Australia, and Dubai, United Arab Emirates.