Prepare the vegetables by washing, peeling, and chopping them as specified.
In a large bowl, combine the chopped romaine, cucumber, tomatoes, red onion, and bell peppers.
Add the feta cheese and Kalamata olives to the vegetable mixture.
In a separate bowl, whisk together the olive oil, red wine vinegar, oregano, salt, and pepper to create the dressing.
Drizzle the dressing over the salad and toss gently to combine everything evenly.
Serve immediately or refrigerate for about 30 minutes to allow the flavors to meld.