Wash the cucumbers thoroughly. Peel off strips of the skin lengthwise to create a striped pattern if desired. Slice the cucumbers into rounds that are about 1 to 1.5 inches thick. Use a small melon baller or a teaspoon to gently scoop out the center of each round to create a “cup” shape, making sure not to go all the way through to the bottom.
In a medium mixing bowl, combine the diced cherry tomatoes, chopped Kalamata olives, minced red onion, and crumbled feta cheese. Toss them gently so the feta doesn’t break down too much. This mixture provides the core flavor profile of the dish.
Drizzle the olive oil and lemon juice over the vegetable mixture. Sprinkle in the fresh parsley, dried oregano, salt, and pepper. Stir everything together until the ingredients are evenly coated. Taste and adjust the seasoning if necessary, keeping in mind that the olives and feta are already quite salty.
Using a small spoon, carefully scoop the filling into each cucumber cup. Press down slightly to ensure the filling stays in place. You can pile the filling slightly higher than the rim of the cucumber for a more generous and attractive look.
Place the finished cucumber cups on a serving platter. If you have extra parsley, sprinkle a little more on top for a fresh finish. Serve immediately or keep them chilled until you are ready to eat.