Add the chopped lettuce, tomato wedges, cucumber chunks, onion slices, halved olives, half the feta and some parsley to a large bowl.
Combine the olive oil, vinegar, sugar, garlic, 1/4 teaspoon salt, pepper and chopped olives in a bowl or mason jar. Whisk or shake together until combined. Taste and adjust seasonings (I almost always add a little more sugar).
Pour the dressing over the salad ingredients, then add some salt and pepper. Toss with tongs or clean hands. Just before serving, top with the remaining feta and squeeze a little lemon juice over the top.