Generously butter a cookie sheet. In a 2-quart glass mixing bowl, using a spoon, stir together granulated sugar and corn syrup. Microwave mixture on HIGH power 4 minutes. Stir in peanuts and salt, microwave on HIGH power 3 1/2 minutes. Mix in butter and vanilla extract, stirring until butter is melted. Microwave on HIGH power 1 1/2 minutes*. Stir in baking soda . Pour and and lightly spread out onto prepared baking sheet. ** Allow to cool at room temperature then break into pieces once set.