Cook the pasta according to the package directions, omitting the salt and fat.
While the pasta is cooking, heat 1 tablespoon oil in a large nonstick skillet over medium heat. Add bell pepper, mushrooms, and garlic, and sauté for 10 minutes. Combine 1 tablespoon oil, vinegar, mustard, and salt in a large bowl.
Drain pasta. Add pasta, salad greens, and mushroom mixture to bowl; toss well. Serve with cheese and black pepper, if desired.