Bacon! – Kill a razorback boar using a Molotov cocktail

You can get this Achievements in the Geothermal Valley. There you can find a Boar and also a Molotov cocktail.

other Rise of the Tomb Raider Achievement Guides

AchievementDesc.
No Stone UnturnedAchieve 100% game completion
Bacon
Quite TImeFind the best seat in the house