Pohotovka Canteen, Prague: The Lunch Queue in Stodůlky
You wouldn't take a date here, and Alcron isn't losing any sleep over the competition: the menu is chalked on a board by the door, and instead of a sommelier, a stack of plastic trays is what waits for you inside. Even so, every single lunchtime a queue forms outside this canteen in Stodůlky, a stone's throw from the Makro wholesale store - workmen shuffling along in it next to white-collar workers from the offices nearby.
Pohotovka Canteen is a self-service tácovka, a tray canteen, serving the classics of Czech cuisine: pick from the board, order it at the counter, and half a minute later you're carrying your lunch to a table.

Hotovka, or Minutka?
Czech pub slang splits hot food into two camps: a minutka only starts cooking once you order it, while a hotovka was ready long before you got hungry. The stigma the hotovka carries is undeserved - the word says nothing more than that the cook worked ahead of your stomach, and its bad name was pinned on it later, by socialist-era standardized recipes and portion weights. Pohotovka put that everyday word straight on its sign and added a prefix.
The Cheap Lunch Is Older Than Socialism
Czech memory files canteens away with cheap lunches under the old regime, but the family tree goes back further than that. The Polish bar mleczny, the milk bar, first opened in Warsaw as early as 1896, as a private dairy business - which means Polish cuisine has been running its version of the canteen for longer than the regime it gets blamed on ever lasted. The Austrian Beisl only half belongs to the family: it will put a cheap lunch menu in front of you, but with waiters and without a tray.
The Czech branch of the family leads to Wenceslas Square: from 1931, Automat Koruna poured drinks from taps there and handed out open-faced sandwiches through glass hatches once you dropped in a coin. Today's return of queues outside canteens has a more prosaic explanation: the average Prague lunch is climbing toward 230 CZK (9.20 EUR), and there's no longer any shame in carrying a tray. If Stodůlky is too far to go, you'll find the same idea at Jídlovice, for instance; Pohotovka itself has been cooking in its present form since 2011, so it wasn't riding any wave.

Six Dishes, Two Soups, One Board
The board carries six main dishes and two soups a day, serving starts at half past ten, and the next day it's gone for good. The repertoire revolves around sure things: Szegedin goulash, vepřový vrabec (pork sparrow) with spinach, sour lentils with two frankfurters and a fried egg, halušky with sheep's bryndza, grilled liver, small sweet buns in vanilla custard. For a moment you're back in the school canteen: plastic tray, napkin, ladle - except the food tastes better and nobody makes you clean your plate. The staff are friendly and, more to the point, fast; you pay by card, you sit inside or out on the terrace, and plenty of diners get their food packed to go. It's open seven days a week - and if you don't like leaving lunch to chance, the day's menu goes up on the website in advance. Hunger can be planned.

Kidneys with Bacon, Dumplings Instead of Rice
I live in Stodůlky, a few minutes' walk from Pohotovka, so the queue isn't something I know from other people's stories - I stand in it regularly, and I'd call it the most reliable cheap lunch in Prague. I've had my usual order many times over: kidneys with bacon, bread dumplings instead of rice, and if there's any room left, half a portion of those buns with vanilla custard. The main course cost 139 CZK (5.60 EUR), the soup 39 CZK (1.60 EUR) (see Where to Eat the Best Czech Food in Prague); I collect more tried-and-tested addresses in my roundup Where to Go for Lunch in Prague. Tomorrow's menu is already up on the website. I know because I checked.
Jídelna Pohotovka