Whisk together first 4 ingredients. Chill at least 1 hour.
Melt butter in a skillet over medium heat; add walnuts, and sauté 5 minutes or until lightly browned. Remove walnuts with a slotted spoon.
Toss together lettuce, pears, asparagus, and toasted walnuts. Sprinkle with cheese and cranberries; drizzle with dressing.
*1 cup broccoli florets or 1 cup snow peas may be substituted.