Cook the quinoa: In a medium saucepan, bring 2 cups of water to a boil. Add the rinsed quinoa, reduce heat to low, cover, and simmer for 15 minutes or until the water is absorbed. Remove from heat and let it sit covered for 5 minutes. Fluff with a fork and let it cool.

Prepare the vegetables: While the quinoa is cooking, dice the cucumber, halve the cherry tomatoes, and finely chop the red onion.

Make the dressing: In a small bowl, whisk together the olive oil, lemon juice, dried oregano, salt, and pepper.

Combine ingredients: In a large bowl, mix the cooled quinoa, cucumber, cherry tomatoes, red onion, and Kalamata olives.

Add dressing: Pour the dressing over the salad and toss gently to combine.

Garnish and serve: Sprinkle the crumbled feta cheese on top. Serve chilled or at room temperature.