2 tsp olive oil, divided
1/2 cup minced onions
1 lb 93% lean ground beef
1/3 cup whole wheat seasoned breadcrumbs
1 large egg, beaten
3 tablespoons tomato paste, divided
pinch black pepper
2 tbsp all-purpose flour
2 tsp red wine vinegar
4 tsp Worcestershire sauce, to taste
1/2 tsp mustard powder
5 oz sliced mushrooms
2 1/4 cup reduced sodium beef broth
1. Finely chop 1 oz of the mushrooms into small pieces and set aside.
2. Heat a large nonstick pan on medium-high. Add 1 tsp oil and onions and cook until golden brown, about 4 to 5 minutes. Divide onions in two.
3. In a large bowl, combine half of the sautéed onions with the ground beef, ground turkey, chopped mushroom, bread crumbs, egg, 1 tbsp tomato paste, 1/4 cup of the beef broth, 3/4 tsp salt and black pepper.
4. In a small bowl, blend flour and 2 cups broth until smooth. Mix in remaining onions, remaining 2 tbsp tomato paste, vinegar, Worcestershire sauce and mustard powder.
5. Gently shape into meatballs.
6. Add remaining teaspoon of oil to the pan and brown the meatballs about 2 minutes until they no longer stick, turn and brown an additional 2 minutes. Add the mushrooms, 1/8 teaspoon salt and black pepper and pour the sauce over the meatballs, cover and cook for 20 minutes or until the meatballs are cooked through and the sauce thickens.