In a medium saucepan, combine quinoa with water. Bring to a boil, then reduce to low, cover, and simmer for 15 minutes until water is absorbed. Fluff with a fork and cool on a sheet pan for 20-25 minutes.

While quinoa cools, prepare vegetables. Dice cucumber and soak diced red onion in cold water for 10 minutes, then drain and pat dry.

In a large mixing bowl, combine cooled quinoa, chickpeas, cherry tomatoes, cucumber, red onion, parsley, mint, and olives. Toss gently.

Make the dressing by whisking together olive oil, lemon juice, minced garlic, Dijon mustard, oregano, salt, and pepper in a small bowl until emulsified.

Pour dressing over salad and toss thoroughly. Gently fold in feta cheese. For best flavor, refrigerate for 30 minutes before serving.

Serve immediately or divide into meal prep containers. Store in refrigerator for up to 4 days with dressing stored separately.