Start by washing the cucumber thoroughly. Cut the cucumber in half lengthwise and scoop out the seeds with a spoon for a less watery result.
Slice the cucumber halves into thin half-moon shapes.
In a large bowl, combine the cucumber slices with salt, lime juice, chili powder, garlic powder, and cayenne pepper (if using). Toss well to ensure all the cucumber pieces are coated evenly.
Let the cucumbers marinate for at least 15 minutes at room temperature or refrigerate for up to 1 hour for a more intense flavor.
Before serving, give the cucumbers another toss and garnish with chopped fresh cilantro.