Rinse and cook the quinoa. Rinse 1 cup of quinoa under cold water for 30 seconds to remove bitterness. Add to a pot with 2 cups of water and a pinch of salt, bring to a boil, then cover and simmer for 15 minutes. Remove from heat, keep covered for 5 minutes, then fluff and let cool.
Prep the vegetables. Dice the cucumber, bell pepper, and red onion.
Halve the tomatoes. Slice the olives. Roughly chop the spinach or arugula if using.
Keep everything bite-sized for easy eating.
Make the creamy dressing. In a bowl, whisk together Greek yogurt, olive oil, lemon zest and juice, garlic, Dijon, and honey. Season generously with salt and pepper. Taste and adjust—add a splash more lemon for brightness or a pinch more honey if it’s too sharp.
Mix the base. In a large bowl, combine the cooled quinoa with the cucumbers, tomatoes, bell pepper, red onion, and olives.
Toss gently to distribute.
Add dressing and herbs. Pour about two-thirds of the dressing over the salad and fold to coat. Add the chopped herbs and crumbled feta, then toss again. If it looks dry, add more dressing a little at a time.
Finish and chill (optional). Taste and adjust salt and pepper.
For best flavor, chill for 20–30 minutes to let everything mingle. Fold in the greens just before serving so they stay crisp.
Serve. Spoon into bowls and top with a sprinkle of extra herbs, a drizzle of olive oil, or a few more feta crumbles.