In a medium bowl, whisk together the rice vinegar, honey and salt. Add the cucumbers and toss to coat with the vinegar sauce. Let sit while the fish cooks.
The Fish:
Preheat the oven to 400 degrees F. Lightly coat a baking dish with cooking spray.
Rub each tilapia fillet with 1 ½ teaspoon olive oil, then sprinkle 1 teaspoon of za’atar on each fillet, coating both sides). Season with salt.
Place the tilapia in the prepared baking dish. Cook until the tilapia is just cooked through, 8 to 10 minutes.