Age of Empires II: Definitive Edition (PC) - Achievement - Dark Dinner
Eat 2 Wild Boars in the Dark Age.
It's very possible to get this achievement naturally as you play, however the first campaign if you are playing in order of release where you can obtain this is the first Attila the Hun mission - The Scourge of God. It's also not a particularly challenging mission making it ideal if you are solely going for the achievement.
As you begin to explore and cross the river to the North, you will come across two boars. Simply send your villagers to kill them and the achievement will trigger - Just remember to stay in the Dark Age whilst doing this as per the achievement requirement.