Use a microplane or the smallest holes on a box grater and grate the dark chocolate very fine.
In a medium bowl, add the grated chocolate, hummus, and ancho chili powder. Stir until combined. Cover tightly and refrigerate for an hour, or until firm.
Use a hinged scoop and measure out 12 truffles on a parchment-lined baking sheet. Chill for 20-30 minutes.
In a medium saucepan, add the chili-infused dark chocolate and melt over low heat, just until melted. Stir until smooth. Using a fork, dip the chilled truffle into the melted chocolate and coat on all sides. Remove to a cooling rack and sprinkle with a pinch of fleur de sel. Repeat with remaining truffles. Chill if not using right away. Allow to come to room temperature for 5-10 minutes before serving.