Slice the cucumber in half lengthwise, then scrape out the pulp with a small spoon. Slice each half lengthwise, then chop into small- to medium-sized pieces. Leaving scallions whole, cut both white and green parts into 1/4 inch pieces. Slice tomatoes in half lengthwise.
Roughly chop olives. Crumble feta.
Slice red onion into paper-thin half moons.
Place cucumber, scallions, olives, grape tomatoes, feta and red onion into large bowl. Add chickpeas. Stir gently to combine.
Add red wine vinegar and olive oil to bowl. Add dried oregano, fresh parsley and lemon zest. Stir again, gently. Add salt and pepper to taste.
Let salad sit at room temperature until ready to serve. If it looks dry, add more red wine vinegar. They key is to keep the salad moist but it should not be swimming in dressing.