Just returned from a six-day stint in London and wanted to pass on the name of a Korean restaurant in Holborn. Asadal (near the underground on Kingsway) proved outstanding: soups, vegetables, dumplings, kimchees, bbq meats and so on were authentic and tasty. Recommend you give this restaurant a shot if you're in the area.
I went for the restaurant's equivalent of the tasting menu (pricey) but you can kick back with the mandoo and bulgogi (all spelling mistakes are my own) and have a terrific meal for reasonable money.
The room is contemporary, clientele was a mix of Korean (mostly) and British professionals. Dress was casual. Seek out the manager (you'll know her when you see her) and share a joke or two.