Load of the level Exodus on Easy difficulty. Play through until you first encounter the Brutes. In this area, you should see a "World Cuisine" kiosk up a staircase, near the first Brute. Head over to this once it is safe to do so. On this kiosk, find the advertisement for Moa Burgers, which cost 7.77cR. Looking at this ad for a second should unlock the achievement (you may have to zoom in on it).
Here's the ad:
Here's the kiosk location:
For reference, Wiljax Brantley is a character in Halo lore who opened a restaurant called Have S'Moa, which sold moa.