Wash and dry the tomatoes, cucumber, and green pepper. Clean off the outer skin from the onion, wash, and dry.
Cut the tomatoes into bite-sized irregularly shaped chunks, removing the core. Slice the cucumber into 1/4-inch slices, cutting slices in half (whether or not you peel the cucumber is a personal choice).
Slice the pepper into rings, removing the stem and seeds. Slice the onion into thin rings.
Combine the tomatoes, cucumbers, green pepper and onion in a large salad bowl. Sprinkle with oregano and salt, pour olive oil over the salad, and toss.
Just before serving, place the feta on top of the salad, either as a slice or crumbled and toss in some olives. Sprinkle the cheese with oregano (and pepper if desired), mix the oil and water and drizzle over the top, and serve, garnished with hot peppers.