In a large heavy saucepan, melt butter and chocolate over low heat. Add sugar, milk, honey and salt. Bring to a boil over medium heat, stirring occasionally. Cover and continue to boil for 2 minutes. Uncover and cook, without stirring, until a candy thermometer reads 240° (soft-ball stage). Remove from the heat; stir in vinegar.
Let cool to 110°. Add vanilla; beat vigorously until mixture thickens and loses it gloss, about 8-10 minutes. Turn onto a buttered baking sheet. Let stand until cool enough to handle. Knead for 2-3 minutes. Shape into 4-in. x 1-1/2-in. rolls. Place on waxed paper-lined baking sheets; chill for 3-4 hours.
In a microwave, melt chocolate chips and shortening; stir until smooth. Dip rolls in chocolate; allow excess to drip off. Roll in nuts. Place on waxed paper-lined baking sheets and chill until firm. Cut into 1/4-in. slices.Yield: about 2-1/4 pounds.