Preheat oven to 375
Rup the olive oil over the meats and bones, roast in oven for 45 minutes, tossing frequently to prevent burning.
Place the meat and all other ingredients in the slow cooker.
Cover all ingredients completely with water.
Cook on high until the liquid is bubbling well, then turn slow cooker down to simmer.
Simmer for 12 hours in the slow cooker.
Once it is done simmering, strain the stock using the strainer and some cheesecloth. Strain it into a large stock pot.
Place in the refrigerator to cool. This will allow the beef fat to solidify on the top of the broth.
Remove the fat from the chilled broth.
Boil the broth down to your liking, to make for a more flavorful and meatier broth.
You can store your broth in the freezer for up to 3 months.