Buchanan strangle

John Buchanan used this technique to win his world bronze medal fight at the Munich World Championships 2001

Speed of entry is the key for the transition to groundwork following an opponents failed attack like drop seoi
From this right hand attack I will push my opponent away to create some space and then go straight for the neck, reaching though for their far lapel with my left hand while controlling them with my body weight.
Stepping over their body and pulling up on their belt. I tuck my right leg into their waist first. I then pull up on their knee as if trying to fold them in half.
the roll then follows which can be either backwards or forwards over the top of them.

At this point the strangle is already being applied but I use my free left leg to push down on their far shoulder to make it even more effective.