Combine the first 3 ingredients in a heavy saucepan over medium heat; bring to a boil, stirring just until sugar dissolves. Cover, reduce heat, and cook 3 minutes. Uncover; cook, without stirring, 10 minutes or until a candy thermometer registers 244°.
Place salt and egg white in a large bowl; beat with a mixer at high speed until foamy. Gradually pour hot sugar syrup into egg white mixture, beating at medium speed, then at high speed until stiff peaks form. Beat in vanilla; stir in nuts. Working quickly, drop mixture by teaspoonfuls on wax paper. Cool completely. Store in an airtight container.