Program the sous vide to 185°F.
Add olive oil, onions, garlic, salt, and pepper to a pan on medium heat and stir for five minutes.
Add beer and reduce to medium-low for 5 minutes.
Pour ingredients in a vac seal bag. Sous vide at 185°F degrees for 2 hours.
Transfer mixture to a pan on medium heat to cook out any remaining liquid. Serve hot or chilled.