The Farside Heelhook is similar to the Scissors takedown that a few people have done in MMA competition. This technique can be used in combination with the Scissors sweep which will raise the percentages of you hitting one or the other.
From the Collar Tie you angle off to the side and hook your lead foot inside your opponents opposite knee to set up the Scissors takedown. Your opponent will feel the Scissors coming if they are familiar with the technique so they step their near foot back to defend.
When your opponent steps back they are clearing the lane for you to go for the Farside Heelhook.
You want to keep pull your opponents neck down as you step in and drop under for the heel hook. The more you can disrupt their posture the greater your chance of finishing the submission.