In 1926, the European correspondent for the Chicago Daily News, Junius Wood, travelled on the Trans-Siberian railway. He had this to say about the cuisine on board:
At 3.30 p.m. a plate of soup appeared - greasy hot water poured over cold pieces of fish that had been cooked earlier in bulk. The next course was pre-cooked cauliflower warmed with a sauce of unknown texture. Roast veal, cooked weeks earlier and now dry and hard, smothered in warm brown gravy, without vegetables, was the main course.
(It was not that much different on some of the trains when Christian Wolmar, author of To the Edge of the World: The Story of the Trans-Siberian Express, the World's Greatest Railroad (from where I got the above quote) travelled on the line in 2012.)