Cook pasta in large pot of boiling water following following package ddirections. Five minutes before the end of the cooking time, add the carrots. Two minutes before the end of the cooking time, add the asparagus. Vegetables should be tender at end of cooking.
Meanwhile, heat the oil in a large, deep skillet over high heat. Add the onion; cook, stirring occasionally, until barely softened, 1 to 2 minutes. Add the mushrooms, salt and pepper; cook, stirring occasionally, until the mushrooms lose their raw look, about 3 minutes. Add red pepper; cook for another 2 minutes. Add peas; cook for another 2 minutes or until everything is tender.
Drain the pasta, carrots and asparagus, reserving 1/2 cup of cooking water. Toss pasta, carrots, asparagus, and reserved cooking liquid together with the sautéed vegetables, sour cream and cheese in a large serving bowl. Serve pasta immediately. Makes 4 servings.