One-Rope Cross Leg Tutorial. I'm demonstrating this as a self-tie but it's the same thing on a partner. This tie uses several key building blocks that you'll see in almost every other rope harness: single column tie, square knot, in-line single column tie / hojo cuff, half hitch, and quick release / bow.
Correction: when explaining different ending options, I described a cinch as a single column tie / hojo cuff. It's the same technique but it would be inaccurate to call it this. The cinch is frictioned with a half hitch in the same way you would if you were creating a hojo cuff.