Salisbury Steak with Mushroom Brown Gravy

Ingredients

• 4 ounces crustless white sandwich bread, diced
• 1/3 cup milk
• 1 teaspoon cornstarch
• 1 1/2 cups homemade chicken stock or store-bought low-sodium chicken broth
• 1 1/2 pounds ground beef, preferably about 20% fat
• 1/2 pound ground pork
• 1 medium yellow onion, half finely minced and half diced, divided
• 2 large egg yolks
• 4 teaspoons Diamond Crystal kosher salt, plus more as needed
• Freshly ground black pepper
• 1 teaspoon onion powder
• 1 teaspoon garlic powder
• 1/4 teaspoon good-quality liquid smoke, such as Wright's or Colgin
• 2 tablespoons vegetable oil or other neutral cooking oil, plus more if needed
• 10 ounces cremini or button mushrooms, stemmed, caps thinly sliced
• 2 teaspoons ketchup or tomato paste
• 2 teaspoons Worcestershire sauce
• 1 tablespoon unsalted butter
• Apple cider vinegar, to taste

Directions

1. Put the bread and milk in a medium bowl, then work them together with your fingers until the bread is fully softened and there are no dry or sturdy pieces left. Set the bowl aside.
2. In a measuring cup or medium bowl, whisk the cornstarch with a couple tablespoons of chicken stock until the mixture is smooth and lump-free. Pour in the rest of the stock, stir again, and set it aside.
3. In a large mixing bowl, add the ground beef, ground pork, minced yellow onion, egg yolks, salt, a very generous amount of black pepper, onion powder, garlic powder, and liquid smoke, if you are using it. Add the soaked bread mixture, including any liquid in the bowl, and mix with clean hands until everything is evenly combined. If you prefer, do this in a stand mixer with the paddle attachment, stopping now and then to scrape the bowl.
4. Pinch off a grape-sized piece of the meat mixture, set it on a small plate, and cook it either in the microwave or in a small nonstick skillet until cooked through, about 15 seconds on high power in the microwave. Taste it, adjust the seasoning if you want, then cook and taste another little sample if needed.
5. Shape the meat mixture into 4 baseball-sized balls; depending on how much you cooked for tasting, there may be a little extra. Press each ball into an oblong steak shape about 3/4 inch thick, and set them on a parchment-lined baking sheet. With your finger, make dimples across the top of each patty.
6. Heat the oil in a large cast iron skillet over medium-high heat until it shimmers. Add the ground-meat steaks with the dimpled sides facing up, then reduce the heat to medium. Cook them until the first side is browned, about 8 minutes, turning them with a thin metal spatula as needed so they color evenly. Flip and brown the second side, about 8 minutes longer, adjusting the heat so they sear without scorching. Keep cooking, turning the steaks every couple minutes, until an instant-read thermometer inserted in the center reads 145 degrees F (63 degrees C). Move the steaks to a platter.
7. Raise the heat to medium-high and add the mushrooms to the skillet. Stir and scrape as they release their moisture, loosening the browned bits from the bottom of the pan, about 1 minute; add more oil at any point if the skillet looks too dry. Keep cooking, stirring occasionally, until the mushroom liquid has cooked off and the mushrooms start to brown, about 6 minutes longer.
8. Add the diced onion and cook, stirring, until it gives off moisture and lets you scrape up the browned bits left from the mushrooms, about 1 minute. Continue cooking until that liquid evaporates and the onion softens and begins to turn lightly golden, about 2 minutes longer.
9. Stir in the ketchup or tomato paste and cook, stirring, for 30 seconds. Stir the stock mixture again to loosen any cornstarch that has settled, then pour it into the skillet and bring it to a simmer, stirring and scraping up the browned bits. Cook until the stock has reduced by about one-third and the sauce is slightly thickened.
10. Add the Worcestershire sauce, then season with salt and pepper. Reduce the heat and add the butter, stirring briskly until it melts and the sauce turns smooth and emulsified, lightly coating the back of a spoon. Add just enough vinegar to balance the sauce, using small additions of about 1/2 teaspoon and tasting after each one so it does not go too far.
11. Return the steaks to the skillet, along with any juices from the platter. Spoon the sauce over the top and simmer gently until the steaks are warmed through. Serve right away.