Place the dates, peanuts, flaxseed, vanilla, and salt in a Vitamix or other high powered blender and, with the aid of the tamper tool process until smooth. Roll the date mixture into 20 balls that are approximately ¾ ounce each (a little smaller than a ping pong ball) and place on a parchment lined baking sheet.
With the palm of your hand flatten each ball to a thickness of about ½ inch. Press 4 evenly spaced pecan halves into each ball, letting the bottom part of each pecan half overhang slightly.
Put the bittersweet chocolate in a microwave safe bowl or measuring cup and microwave on high for 1 minute. Stir the chocolate and put it back in the microwave for 30 second intervals until it is completely melted, stirring after each interval. Drizzle the chocolate over each date/pecan candy. Let chocolate set/harden before removing to a serving platter.