Rinse 1 cup of quinoa under cold running water in a fine-mesh sieve for about 2 minutes to remove bitterness. In a medium saucepan, combine the rinsed quinoa with 2 cups of water and a pinch of salt. Bring to a boil, then reduce to a simmer and cover for 15 minutes.

While the quinoa is cooking, wash and cut vegetables: halve 1 cup of cherry tomatoes, dice 1 cucumber, and finely chop ¼ of a red onion. Optionally, soak the red onion in cold water for 10 minutes to soften its sharpness.

In a large mixing bowl, combine the cooked and cooled quinoa with the prepared cherry tomatoes, cucumber, red onion, and crumbled feta cheese. Stir gently to ensure even distribution.

In a small bowl, whisk together ¼ cup of olive oil and the juice of 1 large lemon. Season with salt and pepper to taste.

Drizzle the dressing over the salad mixture, then toss gently until well-coated, taking care not to mash the feta.

Cover the salad and let it chill in the refrigerator for at least 30 minutes before serving.