1. Preheat the oven to 425°F. Place the scallions, zucchini, bell peppers, and cherry tomatoes in a roasting pan. Season with salt and pepper and toss with the olive oil to coat evenly. Roast for 20 minutes, turning the vegetables once during cooking.

2. Add the corn to the pan and roast for 15 to 20 more minutes, or until the vegetables are very tender and lightly browned. Let cool.

3. Cook the pasta according to the package directions. Drain well.

4. Place the pasta in a large bowl, add the vegetables, and mix well.

5. To make the dressing: In a small bowl, combine the mustard, garlic, lemon juice, sherry vinegar, and salt and pepper. Slowly whisk in the olive oil until blended. Pour over the pasta and vegetables, then sprinkle on the chopped herbs and Parmesan and mix to combine evenly. Taste for seasoning. Refrigerate until chilled before serving.