Preparation

1. Melt the chocolate in the microwave on low power, pausing to stir it every 20 seconds. (Alternatively, you can melt it gently in a double boiler set over a pan of barely simmering water.)
2. Stir the sour cream into the chocolate, mixing vigorously to blend.
3. Add the peppermint extract a bit at a time until you have achieved the desired flavor.
4. Place the truffle mixture in a pastry bag fitted with a star tip and pipe rosettes on a foil or parchment-lined baking sheet. Refrigerate for 30 to 60 minutes, until firm, then place the truffles in paper candy cups.
5. The truffles can be prepared up to two days ahead and stored in the fridge in an airtight container.

Note: If you don't want to use a pastry bag, you can spoon small mounds of the truffle mixture onto the baking sheet, then roll them into smooth balls after chilling. For a pretty finish, roll the balls in powdered sugar or cocoa powder before placing them in paper candy cups.