Grab On A Quetz At Night Knock It Out With A Tribe Member And Be At The Ready At 20:30 To Pick It Back Up And Do It Again. Easiest Method By Far. Have To Knock It Out About 4 Times To Fully Starve But Its Easy Enough This Way.
Dont try taming it on surface (ragnarok) or atleast get some kibble, you need to make it really fast because they lose all the torpor at night. Mine was 87% tamed and suddenly it destroyed my friends and grabbed me, then it killed our pteras, it was a 145 lvl