Chop the onion and grate the carrot.
Cut the red orach leaves into small strips.
Put 3 litres of water in a pot, and add the peppercorn, onion, carrot and red orach leaves.
Bring to boil and simmer for 20 minutes.
Add the rice and boil for more 10 minutes, until the rice is cooked.
Separately, boil the bors.
Add the bors to the soup, gradually, tasting along the way so it’s not too sour.
In a bowl, whisk the egg.
Whilst the soup is still boiling, add the whisked egg slowly, and continue mixing in the soup so it cooks and scrambles quickly. We call this method “egg rags”.
Turn the heat off and serve the soup in bowls, hot, with sour cream on the side.