Now comes the trick. Start with a new mushroom, cleaned and ready to score. This time, as you make the cut, turn the mushroom in your hand. When you finish the cut, it should appear to swoop down from the center to a space a half a centimeter or so to the side. Put the blade in the center again, right next to the cut you just made, and do it again. Remember, you are not moving the knife laterally! It is still making a simple vertical cut into the mushroom cap. You only move the mushroom.