It’s known to all that the hamburger is a popular American food. So, many people think the Americans made hamburgers first. However, people in the US learned to make it from the Germans and the Germans got the idea from the Russians.
Thousands of years ago, the Tartar people from Asia moved into Russia and the place around it. They fought with the Russians and won. They ate something like hamburger meat, but it was raw (生的). This raw meat was beef, mutton and horse meat. Soon the Russians started to eat raw meat, too. Then Germans learned to eat this food from the Russians. But they also ate other things, such as eggs, and then cooked it. Many years later, some Germans moved to the United States and they brought in hamburgers. People called it hamburger steak (牛排). Later, people ate it with their hands, like a sandwich. This was the first real hamburger like the hamburger we eat today.
Now, some people still like to eat raw beef. They call it "steak tartare". Steak tartare is made of raw beef.