Prepare the quinoaCook quinoa according to package instructions, using ½ cup dry to yield 1 cup cooked. If you have frozen pre-cooked quinoa, simply thaw before using. Allow it to cool to room temperature.
Prep the produceCube the watermelon, halve the tomatoes, chop the cucumber, parsley, and mint, and slice the red onion. Chop the olives.
Assemble the saladIn a large mixing bowl, combine the cooled quinoa, watermelon, tomatoes, cucumber, parsley, mint, onion, and olives.
Dress it upDrizzle with olive oil and red wine vinegar, tossing gently so everything is evenly coated.
Season & serveAdd salt and black pepper to taste. If using feta, sprinkle it over the top just before serving. Enjoy immediately or chill for 30 minutes for a colder salad.