Spiral Knot aka Half Knot
A Half knot (or Spiral knot) is the first half of a Square knot. If you tie several in a row, they naturally begin to twist and you get a spiral effect.
Place the left cord over the filler (or holding) cords (the one, or more than one, in the center you are tying onto) then put the right cord over top of the left.
As you continue on tying from the left the spiral will look like this.