Take one ounce of the mushrooms and finely chop them. Set these to the side
Add olive oil to a skillet and toss in the onions, cook until softened
Divide the cooked onions in two portions
In a large bowl combine half the onions with the ground beef and ground turkey, chopped mushrooms, bread crumbs, beaten egg, 1 tbsp tomato paste, ¼ cup beef broth, ¾ tsp salt and the black pepper
In a small bowl blend together the flour and 1 cup of beef broth until this is smooth.
Mix in the remaining onions, tomato paste, vinegar, Worcestershire Sauce and red wine vinegar and mustard powderCarefully form the mix into 20 small meatballs
Add the remaining oil into a pan and saute the meatballs, do the meatballs in batches so as to not overcrowd them. Turn the meatballs over and brown the other side also.
Add in the remaining mushrooms, salt and black pepper.
Pour the sauce over the meatballs and cook for 20 minutes on medium heat. In the crockpot cook 6 to 8 hours on low.
Serve over mashed Cauliflower, mashed potatoes, or rice
