Slice the cucumbers and the red onion on a mandoline slicer to create thin, even slices.
Add the sliced cucumbers and red onion to a medium bowl and set aside.
In a small bowl, whisk together the mayonnaise, rice vinegar, honey, and salt and pepper.
Pour the mayonnaise mixture over the cucumbers and toss well to coat.
Sprinkle the fresh dill on top, toss slightly, and serve.
Notes
This salad is best enjoyed immediately after preparation, or within 2 hours of assembly. To prepare ahead, simply slice the veggies and prepare the dressing separately and assemble before serving.