Combine the beef and marinade ingredients, toss thoroughly to coat and marinate at least 15 minutes
Once beef has marinated, bring a large skillet to medium-high heat, dump the beef and all marinade into the pan and stir fry on all sides, frequently shaking the pan, until deep brown, 5-8 minutes
Remove the beef to a bowl and set aside, leaving as much marinade in the pan as possible
Add the onions to the pan with the garlic and stir fry for 1 minute, scraping up all the beef fond from the pan until the onions begin to soften- we still want them to have snap, this cuts the bite raw red onions have
return the beef to the pan, toss to combine, then remove from heat