Rinse the barley and soak it for 12 hours in cold water.
Boil the barley in lightly salted water for 30-35 minutes, until tender. For taste add the rapeweed oil, apple vinegar, salt and pepper while it is still warm.
Pick the rowanberries off the stem and chop them up. Mix with sugar and a little salt and let them soak for 10 minutes until they make a red, course puré.
Peel the Jerusalem artichokes, apples and carrots and dice finely before folding them in with the barley.
Open and check the oysters, chop coursely and add the oysters and their juice to the barley.
Add the whole mussels. Gently stir in chopped chervil and rowanberries in the barley salad and mix well. If you like, season with a little honey and some extra apple vinegar