In a food processor, combine the garlic, vinegar, extra-virgin olive oil, olive juice, lemon juice, red chili flakes, pepper and all vegetables up to the red onion. Pulse until well chopped but not pureed. Transfer to a bowl, cover with plastic wrap, place into refrigerator and let marinate for 2 to 4 hours.
Add orzo to marinated vegetables, toss, then add feta and toss again.