Hambagu (Japanese Hamburg Steak)

In a large bowl, combine the beef, pork, milk-soaked panko, egg, cooled onion, 1/2 tsp salt, 1/4 tsp black pepper, and a pinch of nutmeg, then knead with your hands for 2 to 3 minutes until the mixture turns pale and sticky.

Divide into 4 equal portions, shape each into a smooth oval patty about 3/4 inch thick, and toss it between your palms 5 or 6 times to expel air pockets, then press a shallow dimple in the center to prevent doming.

Heat 1 tbsp oil in a skillet over medium-high, sear the patties for 2 minutes per side until well browned, then lower the heat to medium-low, add 2 tbsp water, cover, and steam for 5 to 6 minutes until the juices run clear and the center reaches 160°F.

Transfer the patties to plates, then deglaze the pan with the red wine, scraping up the browned bits, and stir in the ketchup and tonkatsu sauce; simmer for 1 to 2 minutes until thickened and spoon over the hambagu.