Wash and dry tomatoes, cucumber, green bell pepper, and lettuce if using
Chop tomatoes into chunks
Slice cucumber into half-moons or chunks
Slice green bell pepper into thin strips
Thinly slice red onion
Pit kalamata olives if needed
Cut feta cheese into blocks or crumble it
Combine tomatoes, cucumber, bell pepper, red onion, and olives in a bowl
Add feta cheese on top
Drizzle with olive oil
Add red wine vinegar or lemon juice
Sprinkle with dried oregano
Add salt and black pepper to taste
Toss gently or serve without tossing
Serve immediately