Sunflower-Seed Brittle

Line a large, rimmed baking sheet with parchment paper and lightly oil the paper. In a medium saucepan, combine the sugar, water and corn syrup and bring to a boil. Boil over moderate heat until the caramel is golden and registers 320° on a candy thermometer, about 10 minutes. Remove from the heat and stir in the butter, salt and baking soda. Stir in the sunflower seeds and quickly spread the mixture on the prepared baking sheet in a thin layer. Let the brittle stand until completely cool, then break into pieces.