Place roast in slow cooker on high.
Pour beef broth and red cooking wine into slow cooker. Add onion. Pour 1 TBSP of the Greek seasoning into the liquid in the crockpot and stir to incorporate. Sprinkle the other 1 TBSP onto the top of the roast. Sprinkle with salt & pepper.
Cook on LOW for about 8 hours. Increase temperature to HIGH and cook an additional 2 hours. OR cook on HIGH for 6-7 hours. If you have time, cook it on LOW for about 13 hours and it's heavenly!