Peel cucumbers and cut in half lengthwise. Using a small spoon, scoop out and discard the seeds.
Sprinkle cucumbers with salt (if desired) and set at room temperature for 15 minutes. Rinse cucumbers and pat dry with paper towels.
Slice cucumbers into 1/4-inch thick crescents. Sprinkle with cornstarch and set aside.
Meanwhile, lightly coat a large nonstick skillet with cooking spray and place over medium heat. When hot, add the cucumbers and cook, stirring occasionally, until cucumbers are crisp-tender, about 3 to 4 minutes.