Ok here it is.
Step 1: Tie an overhand (Granny) knot in the heavier material and pass your lighter line through.
Step 2: Pull the overhand knot in the heavy line tightly closed. Take four or five turns around the heavy line with the light.
Step 3: Pass the light line back through the first loop as shown.
The illustration shows one overhand granny in the heavier standing line for use as a shock leader. In a braid to mono or flouro leader the granny is in the leader. The braided line clinch gets more wraps and the improvement by passing the tag end through the last loop. This knot is as strong as hell and so far has held up for me.