The matjes (preferably in June, soak the late matjes a little beforehand) first into thin strips and then into fine cubes. Finely dice the onion and cucumber, finely grate the ginger, finely chop the capers and dill.
Mix the spices and all the other ingredients together with the matjes, season with cognac and lemon juice and let steep for at least 30 minutes.
Arrange on Rhenish black bread thalers or lukewarm crostini and serve immediately. A fresh, dry white wine or a cool blond go very well with it.