To make the Zesty Italian Dressing, combine the oil, vinegar, water, sugar, oregano, garlic powder, onion powder, thyme, basil, red pepper flakes, and pepper in a small cruet or lidded container. Shake well to mix.
To make the salad, add the quinoa, tomatoes, mozzarella, cheddar cheese, bell pepper, onion, olives, mushrooms, and pepperoni to a large bowl. Stir to combine.
Drizzle the dressing over the salad. Toss to coat.
Notes
Storing: Either cover and store the salad in the large bowl or divide the salad between 5-6 lidded containers. Store in the refrigerator for up to 5 days.