Clean, wash and cut the rhubarb into pieces. Wash and clean the strawberries. Cut strawberries into quarters, except for 4 pieces. Boil up rhubarb, lemon juice and 150 ml water. Cook everything for 5 minutes at low heat.
Stir starch in a little cold water until smooth. Add strawberries and 40 g sugar to the rhubarb. Stir in the starch and bring to the boil. Put compote in a bowl and let it get cold. Stir quark, eggs, flour, baking powder, pudding powder, semolina, lemon peel and remaining sugar until smooth.
Bring light salted water to the boil. Form 12 dumplings from the quark dough with floured hands. Put them into boiling water and let them simmer for 12-15 minutes at low heat. Arrange 3 dumplings each with some rhubarb-strawberry compote on a plate.
Decorate with lemon, remaining strawberries and lemon balm.