Cook the pasta in boiling water for 11 minutes or until cooked but still firm, stirring occasionally. Do not overcook.
Put the cooked pasta into a sieve and rinse under cold water. Drain well. Place in a large bowl. Set aside to cool.
Whisk the mayonnaise, mustard, lemon juice, wine vinegar, olive oil, garlic, pepper, salt, and feta cheese together in a bowl or large measuring cup.
Just before serving, pour the mayonnaise mixture over the cooled cooked pasta. Stir gently to coat the pasta with the dressing.
Stir in the chopped green onions, tomatoes, and olives.
Transfer to a serving dish. Sprinkle the chopped parsley over top.
Makes 4 to 6 servings