Combine garlic, mayonnaise, lemon zest, lemon juice, red wine vinegar and salt and pepper in a medium bowl. Slowly whisk in the oil until emulsified.
Slice cucumber lengthwise and slice very thinly into half rounds. Combine the cucumber, olives, oregano, tomatoes, onion, feta, and romaine in a bowl. Add some of the dressing and toss to coat, season with salt and pepper.
Spread some of the dressing over the entire surface of the bread, top with some of the salad and sprinkle some grated lemon zest and chopped parsley. Roll and eat or serve open face on a large plate.