Preparation - In a 1 1/2 quart casserole, stir sugar and corn syrup together. Microwave on full power for 4 minutes. Add peanuts and stir. Microwave on full power for 3 to 5 minutes or until lightly brown. Add butter and vanilla, and stir to blend well. Microwave on full power for 1 to 2 minutes. Add baking soda and stir until light and foamy. Spread on a buttered baking sheet. After candy hardens, break into pieces. Store in an air tight container.