Wash and cut the cucumber lengthwise. If the seeds are big, take them out. Then, slice into thick halves (about the thickness of pinkie finger).
Wash and cut the tomatoes into large wedges (at least 1.5 cm, 0.6inch thickness).
Cut the red onion in half and thinly slice it.
Slice the green bell pepper into rings.
Place all the ingredients in a large bowl.
Add the salt, pepper, olive oil, red/wine vinegar, and 1 teaspoon of the oregano, and gently toss the ingredients, so that everything is coated with the olive oil.
Add the Kalamata olives, the feta cheese cut in sticks, cubes or triangles, and the capers.
Sprinkle the rest of the oregano, drizzle with some extra olive oil, and serve.