Cut the beef in cubes.
Put it in a pot of 5L of cold water, and simmer for 40 minutes to one hour, until the meat becomes tender. Test it with a fork. If the fork goes into the meat easily, you can move to the next step.
Make sure to clear the foam that forms on the top of the soup when it starts boiling.
Add the chopped onion, celery, and carrot.
Let the soup simmer until the root vegetables start to soften up, 15 minutes or so.
Add the chopped potatoes, green beans, and pepper.
Meanwhile, boil one cup of bors separately. When it starts boiling, take it off the heat.
After 15 more minutes of simmering, add the can of chopped tomatoes.
Let it boil for 5 minutes, and then add the bors. Let the soup come to a boil, and then turn the heat off.
Add the finely chopped herbs and mix them well in the soup.
Serve the soup hot alongside sour cream.