Cheese Stuffed Japanese Hamburger Steak

Before You Start...

1. Please note that this recipe requires 30 minutes of inactive resting time (patties in the refrigerator) in addition to the total active cooking time.
2. Gather all the ingredients. If doubling the recipe, please cook one batch at a time in the pan.

To Make the Patties

1. Finely mince ½ onion (we call this cutting technique mijingiri in Japanese). Lay a half onion flat side down on the cutting board. With the knife edge toward the root end, make ⅛-inch horizontal slices to within ½ inch of the root end to keep it intact. Next, with the knife tip pointing toward the root end, make ⅛-inch vertical slices to within ½ inch of the root end.
2. Finally, make perpendicular cuts down through the vertical slices you made. If you need to chop the onions finer, run your knife through them using a rocking motion. Hold down the tip of the knife; otherwise, the onions will go flying around the room.
3. Heat a large pan over medium heat. When the pan is hot, add 1 Tbsp neutral oil. Then, add the onions.
4. Sauté the onions until tender and almost translucent.
5. Transfer to a large bowl and let it cool.
6. Once the onions are cool, add the ¾ lb ground beef and pork combination to the bowl. Add ⅓ cup panko (Japanese breadcrumbs), 2 Tbsp milk, and 1 large egg (50 g each w/o shell). Then, add ½ tsp nutmeg, ½ tsp Diamond Crystal kosher salt, and freshly ground black pepper as you like. Tip: You can make hambagu with 100% beef, but it will not be as juicy and tender as combining the two meats.
7. Start mixing it all together with a silicone spatula or spoon.
8. Then, switch to mixing by hand and knead the mixture until it‘s sticky and pale.
9. Divide the mixture into 4 portions (4 oz, 113 g each) or 6 smaller portions. Scoop out one portion.
10. Toss it from one hand to the other repeatedly about five times in order to release any air inside the mixture (see the video link above). Tip: Without releasing the air inside, the hamburger steaks will likely crack while cooking.
11. Make an oval-shaped patty and place on a tray or plate. Repeat with the remaining portions. Then, prepare the cheese filling by dividing 1 slice Provolone cheese into 4 (or 6) portions.

To Add the Cheese Filling

1. Pick up one patty and use your fingers to flatten the center a bit. Then, place one portion of cheese in the center of the patty.
2. Use both hands to close the meat around the cheese filling. Seal the meat around the cheese and pat to reshape into an oval patty. Place on a tray or plate.
3. Continue until you‘ve finished stuffing all the patties. Cover the patties with plastic wrap and keep them in the refrigerator for at least 30 minutes before cooking so that the meat combines well and the fat solidifies.

To Cook the Cheese Hambagu

1. Heat a large pan over medium heat. When the pan is hot, add 1 Tbsp neutral oil. (Cook one batch at a time if you‘re doubling the recipe.) Place the patties gently into the pan.
2. Indent the center of each patty with two fingers because the centers will rise with the heat.
3. Cook the patties until browned on the bottom side, about 3 minutes. Then carefully flip and cook for another 3 minutes until browned.
4. Add 3 Tbsp red wine and reduce the heat to low. Cover the pan with a lid and cook for 5–7 minutes to thoroughly cook the inside of the patties (adjust the cooking time depending on the thickness of the patties).
5. Uncover and check that it‘s fully cooked by pressing the hamburger steak with the spatula. If clear juice runs out, then it‘s done. Increase the heat to medium to let the alcohol finish evaporating. When it’s almost finished, transfer the hamburger steaks to individual plates. Do not wash the pan as you will make the sauce next using the pan juices.

To Make the Red Wine Reduction Sauce

1. To the same frying pan, add the sauce ingredients (for one batch): 1 Tbsp unsalted butter, 3 Tbsp ketchup, 3 Tbsp tonkatsu sauce, 3 Tbsp red wine, and 3 Tbsp water. Tip: Since some ketchup is sweeter than others, adjust the amount to taste. For the tonkatsu sauce, you can substitute Worcestershire sauce and sugar in a pinch.
2. Mix well together and bring the sauce to a simmer over medium heat. Let the alcohol evaporate.
3. When the sauce thickens and you can draw a line on the bottom of the frying pan with a spatula, remove from the heat. Drizzle some sauce over the cheese-stuffed hamburger steaks.

To Serve

1. Pour the remaining sauce in a small bowl or jar and bring it to the table for serving. We typically serve this dish with Steamed Rice, Homemade Miso Soup, and steamed vegetables or a salad. It‘s also delicious served with baked potato wedges or Japanese Potato Salad and Corn Potage (Japanese Corn Soup). Enjoy!

To Store

1. Transfer the leftover hamburger steaks to an airtight container and let them cool completely. You can store them in the refrigerator for up to 3 days and the freezer for up to a month.