Place the mushrooms, garlic, and remaining onion in the skillet and sauté until the onion begins to turn translucent. If the skillet starts to get dry, add a little more oil.
1 onion, 12 mushrooms, 4 garlic cloves, 1 tablespoon olive oil
Add the broth, ketchup, apple cider vinegar, salt, and spices to the sautéed vegetables and stir.
2 cups beef bone broth, 1/2 tablespoon ketchup, 1 teaspoon apple cider vinegar, 1 teaspoon dried sage, 1 teaspoon dried parsley, 1 teaspoon salt
Place the patties back in the skillet, and gently simmer on low to medium heat until the sauce has reduced to your preferred consistency.