What about a traditional greek salad. Just cut up onions, green peppers, cucumbers and tomatoes. Sprinkle with oregano and garlic salt, crumbled feta, then put balsalmic vinegar and olive oil. You can eat it with fish, it is a great side dish.
Also, greek yogurt dip. Get a large tub of plain yogurt, strain it for several hours with a cheese cloth, so it get thick. Grate a cucumber and finely chop garlic. Mix together with some lemon juice and olive oil. You can dip pita bread in it or veggies. Also, you can roast red peppers and dip those in it. Or use it as a spread for meat or fish.
I bet there are a ton of other greek recipes with those ingredients, I'll check my cookbooks.