Arrange the red onions, eggplant, red peppers, and tomatoes on a large baking sheet; drizzle with 2 tablespoons olive oil and season with salt and pepper. Roast for 20 minutes.
Combine the spinach and arugula in a large bowl with the remaining 1/2 tablespoon olive oil and the vinegar.
Add the roasted vegetables and toss.
Transfer the salad to a plate. Top with salami, Parmesan cheese and gently toss.