1. You need to feed it element to Tame it. The first time is easy. Wait for it to do AND FINISH its emote and then feed it.

2. Survive it's enlarged form (it could be useful to trap it.)

3. Once it transforms back it will lay on the ground for a bit use that to get DISTANCE to it. It should run towards you for a bit don't stand right next to it. My testing proofed that staying away from it after it shrinks and letting it walk towards you greatly increases the chance for it to make it's emote right away which is what you need to wait for otherwise you will waist one element.

4. (just in case step) if it walks up on you and doesn't do the emote it will look at you for a moment and then run away. Once it runs away immediately run up to it and feed it element. That has the same effect as it doing the emote.

With the new Taming hud menu, Taming process can only be seen when it is small and everytime it transforms from small to big and big to small the marker is automatically removed.