01 -
Season both sides of the beef slices evenly with salt and black pepper.
02 -
Place half of the sliced sweet onions and half of the minced garlic into the bottom of a 6-8 quart slow cooker.
03 -
Arrange the seasoned beef slices over the onions and garlic, then sprinkle the brown gravy mix evenly on top.
04 -
Distribute the remaining sliced onions and minced garlic over the beef, then pour in the unsalted beef stock.
05 -
Cover and cook on low heat for 7 to 8 hours, or on high heat for 5 to 6 hours until the beef is tender.
06 -
In the final 30 minutes, remove approximately ½ cup of cooking liquid. Whisk in the cornstarch until smooth, pour the mixture back into the slow cooker, increase heat to high, and cook uncovered until the gravy thickens, about 30 minutes.
07 -
Stir to combine and serve immediately, preferably over mashed potatoes or rice.