To prepare the dressing, whisk together tomato paste, olive oil, vinegar, Italian seasoning, and salt in a small bowl. Set aside.
Cook couscous according to package directions. When done, remove lid and allow to cool for at least 10 minutes before mixing with other ingredients.
Meanwhile, arrange squash and zucchini in a single layer on a baking sheet lined with aluminum foil and sprayed with cooking spray. If you are using fresh mushrooms, include them here as well. Lightly sprinkle vegetables with seasoned salt or salt and pepper, then broil or roast at 400 degrees F for 7-10 minutes. (I do this part in my toaster oven.)
In a large serving bowl, stir together salami, artichoke hearts, tomatoes, cheese, mushrooms, and roasted vegetables. Add dressing and couscous, and gently stir together until well combined. Serve immediately, or refrigerate until ready to enjoy.