Cook the quinoa according to package directions.
Once cooked, fluff with a fork and transfer to a large mixing bowl to cool slightly.
While the quinoa cooks, prepare the dressing.
In a small bowl, whisk together the minced red onion, balsamic vinegar, extra virgin olive oil, sea salt, and pepper.
To the bowl with the quinoa, add the halved tomatoes, sliced basil, and halved mozzarella balls.
Pour the dressing over the salad and toss gently to combine everything.
Serve immediately at room temperature for the best flavor.