Crockpot Barbacoa

FOR THE BEEF: 3 lb. Pleasant Valley chuck or rump beef roast (that’s my bit for advertising, but it is really, really good meat) 1 onion, chopped 1/4 cup apple cider vinegar 6 garlic cloves, chopped 2 T. whole black peppercorns 2 bay leaves FOR THE SAUCE: 1...