First prepare the dressing. Put the mustard and balsamic vinegar in a small bowl and season with salt and pepper. After stirring, gradually add the olive oil. The dressing should be viscous. Add a little dill to taste.
Peel the cucumber, cut in half lengthways and core. Then halve once across, cut these halves into fine strips and the strips across into small cubes. Put the cubes in the dressing and let it steep.
In the meantime, wash the tomatoes and cut them into fine slices. Arrange overlapping on a plate from the outside in and season with a little salt.
Arrange the cucumbers nicely on the tomato carpaccio with a ring or another shape. A bit thick, dark balsamic vinegar or fresh dill are suitable as decoration.