one of my favourites actually!

here's how it's done:

2 tablespoons olive oil
1 tablespoon lemon juice
3 tomatoes—cut into wedges
1/4 red onion: "ring"ly sliced
1/2 cucumber: tickly sliced
1/2 green pepper
120g feta cheese - cut into cubes
16 olives

ofcourse salt & pepper, oregano too if you would like

shake the olive oil, lemon juice, (salt, pepper & oregano) alltogether in a jar
put the vegetables in a big bowl and throw the dressing above them and go eat