Preheat the oven to 375F.Toss together the tomato, onion, garlic, 1 tablespoon extra-virgin olive oil, 1/4 teaspoon salt, and black pepper in an 8 by 8-inch casserole dish. Cover the dish with foil and roast until the veggies are tender and starting to brown in spots, about 45 minutes; cool slightly.Add the roasted veggies, remaining 3 tablespoons extra-virgin olive oil, remaining 1/4 teaspoon salt, balsamic vinegar, and water to a blender and process until smooth. Stir in the Italian herb seasoning.
For the Pepperoni Chips:
Arrange the pepperoni in a single layer on a large baking sheet and bake until crispy (TIP: no oil needed), about 8 to 10 minutes at 375F. Transfer the pepperoni to a paper towel-lined plate to drain any excess oil. (TIP: Bake the pepperoni at the same time that you roast the vegetables for the dressing, just remember to set 2 timers.)
Serve:
Arrange the spring mix on 2 plates. Top each with the red bell pepper, red onion, mushrooms, pepperoni chips, and Parmesan cheese. Drizzle some dressing on each and serve immediately (TIP: you'll have extra dressing; see Notes).
Notes
Dressing Storage and Other Ways to Use It: Store the leftover dressing in a covered glass jar in the fridge for up to 1 week. You can toss it with pasta or use it a dip for veggie sticks, a spread on sandwiches and wraps, a condiment for eggs, etc.
Nutrition Information: The nutritional information for this recipe includes the salad components only (not the dressing). If you use about 1/4 of the dressing, it adds approximately: 162 kcal, 8 grams carbs, 2 grams fiber, 1 grams protein, and 14 grams fat.