This sequence is also shown in a short video.

Drive the motorcycle around to the back (north) entrance to the CHAMBERS and carefully position it in the corner of the raised ledge, as shown in these screenshots.

Make sure there's a little space between the sidecar and the ledge, so that Lara will be able to walk to the edge without bumping into the sidecar.

You want to be able to jump straight up and grab the ledge above (i.e., the ledge near the entrance to secret #1).

Now run to the end of the street to the west and round the corner...

...to get the Minotaur's attention.

instead of luring him into the CHAMBERS, run back to the ledge where you parked the motorcycle. Walk to the edge and jump straight up to grab the ledge above (as shown in the previous screenshots).

The Minotaur should approach and start pacing around directly beneath Lara. Traverse to the left a little so Lara is holding onto the edge of the gray slope.

Then let go and drop. Ideally you want the Minotaur to try and attack Lara. If he loses interest and runs away, the bug won't work. So pause here just a moment and let him rage.

Then run off the edge...

...and get on the motorcycle as quickly as you can.

If your timing is good, and the Minotaur hasn't lost interest and run off, the bug should kick in. Because the Minotaur is so close to the front of the motorcycle, the game interprets this as his being run over, and he drops dead on the spot. Now you're free to explore in peace.

[Chambers of Tulun Walkthrough]