Place asparagus and 2 tablespoons water in a microwave-safe dish. Cover and microwave on high for 2-4 minutes or until crisp-tender, stirring once; drain and cool.
In a large bowl, combine the asparagus, mushrooms, avocado, zucchini, tomato and onion; toss gently. In a jar with a tight-fitting lid, combine the remaining ingredients; shake well. Pour over salad and toss gently to coat. Cover and refrigerate until serving. Yield: 7 servings.