Using a channel knife, peel off a few strips of cucumber skin to create a striped pattern. Cut the cucumbers in half crosswise, then quarter each half before slicing into 1/4- to 1/2-inch pieces. Place in a colander, toss with kosher salt, and let sit for 10 to 15 minutes.

Halve the cherry tomatoes. Rinse the cucumbers and drain thoroughly for an additional 10 to 15 minutes.

Thinly slice the onion, cut the bell pepper into strips, and then dice the strips into diamond-shaped pieces. Slice the Kalamata and green olives.

In a large bowl, combine the cucumbers, tomatoes, onion, bell pepper, olives, and 2 tablespoons of oregano. Season with salt, black pepper, and cayenne. Add the vinegar and toss well. Drizzle in the olive oil, add most of the feta cheese, and toss again. Cover with plastic wrap and refrigerate for 30 to 60 minutes.

Give the salad a final mix, taste, and adjust the seasoning if needed. Sprinkle the remaining feta cheese on top and garnish with the remaining oregano before serving.