Place a pot with plenty of water. Salt the water, add the pearl barley and simmer slowly until soft.
Heat a sous-vide bath to 52°C.
Portion each char side into 4 pieces and salt. Place each 4 pieces in a vacuum bag, seal airtight with the vacuum pump from the VAKO vacuuming set and place in the water bath. If necessary, weigh it down a bit so that the fish is completely covered with water. Let the fish steep for about 6-8 minutes, depending on its size.
Remove the beet from the package and collect the juice. Cut the beet into eighths. Heat some butter in a pan. Add the beet with 1 tablespoon of the beet juice and some vinegar and toss in the pan. Season with salt and pepper.
Put the pearl barley in a sieve and drain. Arrange in deep plates and garnish the beet around.
Remove the vacuum bag from the water bath, open it, take out the char and put it on the pearl barley. If necessary, salt a little and grate the fresh horseradish over the plates.