During that period of the Qin Dynasty, the most common foods were grains and vegetables. At that time, there was not much ability to grind them into flour, and rice was not common, only wheat. But at that time, wheat was used to cook porridge or steam rice. At that time, there were few vegetables, only vegetables such as bitter vegetables, leeks and shallots, and others were wild vegetables.
As for beef, it is absolutely inedible. In Qin dynasty, cattle were very important crops. If someone is found to have killed a cow, the court will arrest him, then punish him and finally behead him. So at that time, people ate pork or chicken the most, or they could choose to hunt in the mountains or catch fish in the river.
But if the monarch of Qin wants to eat beef, there is absolutely no problem, because every monarch has his own royal land, and the beef and mutton raised by the royal family are for the emperor, so only the people can't eat beef at that time, and the emperor can't eat it. So it was ok for the emperor to eat beef at that time, but it must not be put on the people.
Generally speaking, cows were really precious at that time. It is impossible for ordinary people to eat, but for the monarch, it is no problem to eat stewed beef. There is nothing wrong with such rendering or depiction in film and television dramas. We should be proud of living in such a happy era.