Using a mandolin, slice the cucumbers and zucchini into thin even slices. You can also use a food processor or a chef's knife if you don't have a mandolin. To get even bite-size pieces, cut the zucchini slices lengthwise and crosswise (if you're using an English cucumber, you will have to do the same thing with the cucumber).
Transfer the sliced veggies into a bowl and give it a quick toss to separate all the slices.
Chop the jalapeno (or Serrano) chili pepper, and cilantro, and add it to the bowl together with olive oil, lime juice, salt, and black pepper. Mix until combined.
Place the bowl with the salad into the fridge for a couple of hours. This step is optional, but it will allow the vegetables to soak up all the flavors from the dressing.
Store leftover salad covered in the refrigerator for a few days, though best within the first 24-48 hours.
Notes
*You can swap 2 Persian cucumbers for 1 English cucumber.