Add chopped lettuce, tomato wedges, cucumber chunks, onion slices, halved Kalamata olives, half the feta, and parsley to a large bowl.
Combine olive oil, vinegar, sugar, garlic, salt, pepper, and chopped olives in a bowl. Whisk together until combined. Taste and adjust seasonings (I almost always add a little sugar.)
Pour dressing over salad ingredients, then add salt and pepper. Toss with tongs or clean hands. Just before serving, top with additional feta and squeeze a little lemon juice over the top.