Butter a large baking sheet; set aside. Cut nuts in half; set aside.
In a 10-inch nonstick skillet, combine sugar with 1/2 cup water and cornsyrup. Cook over medium-high heat, stirring occasionally, until golden brown.
Stir in nuts; cook, stirring constantly, until medium brown (do not burn mixture). Remove from heat; quickly stir in butter and baking soda. Pour onto prepared baking sheet. Cool on pan on wire rack. Break into pieces.
