Set Mandoline round knob to #3, triangular knob to �lock� and select the straight v-shaped blade insert. Using food guider, slice both cucumbers, discarding the ends. Transfer to medium bowl.
Season and serve
Switch Mandoline round knob to #1, and use food guider to slice onion. Add to cucumber in bowl. Add tomatoes, feta and balsamic dressing to cucumber mixture and toss gently to combine.
