There is very easy guide how to complete “TRESSLER – HUNTING FOR GOLD” mission.
Hunting For Gold Mission Guide
The process of the mission
At the beginning you should find group of animals at least 4. Next you have to kill them in the same area until you get pink/purple colour like in this picture below.
The best tactic is lure 4 Fallow Deers > kill 1 > use decoy > repeat 3 times > done
Congratulations! Hunting For Gold(TRESSLER) missions done.
Does it matter where you do this? I have taken down multiple game in the straw fields – roe deer, boars, fallow deer and foxes. The map is pink and purple, but I still don’t get credit for the mission.