Line cookie sheet with foil; lightly butter foil. In 8-cup microwave-safe measuring cup or medium microwave-safe bowl, combine sugar and corn syrup. Microwave on HIGH for 4 minutes.
Stir mixture. Add nuts; blend well. Microwave on HIGH for 3 1/2 to 4 1/2 minutes or until mixture is very light brown.
Stir in butter and vanilla. Microwave on HIGH for 1 minute.
Add baking soda; stir quickly to blend. Pour immediately onto buttered foil-lined cookie sheet, spreading mixture quickly with wooden spoon. Cool 30 minutes. Break into pieces; store in airtight container.