Place sugar, corn syrup, water, salt and peanuts in 2 quart microproof bowl or casserole. Cook on High (maximum power) for 5 minutes, then stir. Cook on High (maximum power) for 13 to 15 minutes or until syrup separates into threads. This is the hard-crack stage or 300 degrees on a candy thermometer. Check temperature with thermometer several times during the last few minutes. (Do not leave thermometer in oven while cooking.) Stir in butter, baking soda and vanilla just until light and bubbly. Pour onto buttered cookie sheet. Spread. Cool and break into pieces. Makes 1 1/4 pounds. Note: You may use either light or dark corn syrup. The color of the peanut brittle will differ, but both are delicious. Posted to recipelu-digest Volume 01 Number 363 by "Diane Geary" on Dec 12, 1997