In a shallow dish place the flour, pepper and garlic powder and stir with a fork to combine.
Toss the beef tips in the flour mixture to coat on all sides and set aside.
On the stove-top, heat a large skillet until very hot and then add 2 tablespoons olive oil.
Add the floured beef to the pan and sear the meat and brown it on one side for about 4 to 6 minutes. Then flip the meat over as best as you can (I just use a spatula and give it a turn) and allow it to brown on that side for another 4 to 6 minutes.
Remove beef from frying pan and transfer to a 5 to 6 quart slow cooker.
In the same pan add an additional 1 tablespoon of olive oil and the chopped onions, and cook them until they are translucent and slightly browned (10 to 15 minutes).
Add cooked onions to the crock-pot.
Deglaze the pan in which you cooked the beef and onions with some of the beef broth, making sure to scrap up the browned bits and pour off the liquid into the crock-pot with your beef and onions.
Add the rest of the beef broth, red wine and brown gravy mix and stir everything to combine.
If you wish to add sliced mushrooms now would be the time to add 8 oz. sliced white or baby portobello mushrooms to your slow cooker.
Cover your slow cooker and cook on LOW temperature for 6 to 8 hours.
Give everything in the crock a final stir and serve over cooked white or brown rice or cooked egg noodles for a lovey dinner and enjoy!