In a 2-quart saucepan, heat the couscous and one tablespoon of olive oil over medium-high heat for 5 minutes, toasting the couscous. Stir often.
Add 1 ¾ boiling water to the couscous. Bring to a boil, then reduce heat. Let simmer, covered, for 12 minutes, or until all the water is evaporated.
Meanwhile, toss the zucchini and tomatoes with a tablespoon of olive oil and salt and pepper. Place on a parchment-lined, rimmed baking sheet and bake for 15 to 20 minutes, or until the tomatoes have burst and the zucchini is lightly browned.
Combine the remaining olive oil, lemon juice, balsamic vinegar, and salt and pepper in a small bowl. Whisk to combine.
Combine the couscous, vegetables, mozzarella, and vinaigrette in a large bowl. Garnish with the herbs and drizzle the balsamic glaze across the top.
Notes
Storage - save leftover pasta salad in the refrigerator for up to 4 days in an airtight container.