Is the Blue Nile, TripAdvisor's 'best' restaurant in London, really that good? I had lunch in London's "best" restaurant today. It's a humble Eritrean cafe on Woolwich New Road in south-east London, sitting in the shadow of a vast branch of Tesco, which, in a roundabout way, is responsible for the Blue Nile cafe's very existence. When I say it's the capital's "best" restaurant, that's according to TripAdvisor. The site's rankings are dynamic, and change according to the number of positive reviews posted - as well as how recent they are, so by the time I arrive for my lunch, it's down to No 4 of 17,434, but that's still above the likes of Le Gavroche and Restaurant Gordon Ramsay. TripAdvisor's random restaurant rankings mean the site is regularly mocked by restaurateurs, chefs and restaurant critics. I fall into the latter category. You can't reduce restaurant rankings to an algorithm, even when those submitting the reviews supposedly know what they are talking about. Never mind if - as is the case with TripAdvisor - it's a bunch of random punters who can't rate what they are eating in the context of other restaurants that do the same thing for the same price. Talking about "best" is nonsense. Best for what exactly? All lists are crude cultural fascism and those containing restaurants are no exception. I should know. I was responsible for the original feature that went on to become the juggernaut that is the world's 50 best restaurants. That is currently topped by Noma, a restaurant that deserves all the attention it gets, even if the list and its rankings are fundamentally flawed. The Blue Nile. Photograph: Linda Nylind/The Guardian The good news is that the Blue Nile is a lovely place. It serves some of the best Eritrean food I've eaten in London. We have a selection of dishes - fragrant lamb and beef stews, and two different lentil dishes packing a decent amount of heat. And it's all served with the splendidly sour injera bread cooked fresh on the premises each morning, and deployed to mop up the sauces - there are no knives and forks here. "The food doesn't taste right without injera," explains the Eritrean owner, Shewa Hagos. And she's right, the pleasantly sharp taste complements the blend of spices used in the kitchen - korerima (a particularly pungent variety of cardamom), chilli, turmeric, tikur azmud (black cumin) and nech azmud (white cumin). Eritrea has an Italian colonial past and it shows here on the menu. It's in the short all-Italian wine list, the specials of lasagne on the blackboard and the excellent tiramisu we have for dessert. With a decent bottle of Sangiovese and tip, lunch for two came to £35. Hagos opened the Blue Nile in January this year. It was born out of the failure of the previous business on the premises, a sandwich bar called The Salad Bowl - whose name still appears on the cafe's credit-card receipts. The arrival of Tesco and competition from pound shops doing cheap sarnies was killing the business. Food from this part of the world is still relatively unknown and in Hagos, who arrived in London in 1982 as a refugee, it has a fine ambassador. She is a smart, resourceful woman and a walking, talking (she likes to talk) argument against Ukip. One of her sons is an architect and has helped to turn what was once a butcher's shop into a very cool little dining room on a tight budget. The false ceiling has been torn down to reveal the original barred skylights. The tiled walls are decorated with vintage maps and backlit posters. Food on offer at the Blue Nile, including the fermented injera flatbread. The best restaurant in London? Never was, never will be. But it's an unexpected gem in an unlikely setting. The Blue Nile and Hagos deserve all the attention they're getting. Having vowed to disregard rankings and lists full of crude, unqualified generalisations, I'll just have to come to terms with the fact I found out about the place because of TripAdvisor.