In the Vortigaunt village(where a Vortigaunt lets you into the village by disabling a forcefield that blocks you from entering), after the fight with the Controllers, walk through the vent by the entrance and you'll see another elevator.
Immediately after getting out of the vent and standing up, and before entering the elevator visible straight ahead, turn left and you'll see two crates. Break them. Go through the entrance that was hidden behind them, and all the way up.
An ammo supply cylinder will be teleported into the room. But instead of ammunition, it contains snacks! The achievement will pop!