1In a large pot with boiling salted water cook spaghetti pasta until al dente. Drain.
2Meanwhile, in a large skillet heat olive oil over medium heat. Add onion, garlic, basil, sliced mushrooms, and chopped tomatoes and cook for 5 minutes. Stir in California-style vegetables, salt, and ground black pepper. Cook for approximately 10 minutes, stirring often, until vegetables are tender and crisp.
3Pour vegetable mixture over cooked and drained pasta. Toss well. Sprinkle with grated Parmesan cheese and serve.