1
Finely mince a yellow onion.
2
Saute the onion on low to medium heat until caramelized.
3
Soak panko in heavy cream for 20-30 minutes.
4
In a large mixing bowl, combine ground pork, ground beef, panko, eggs, onions, salt, pepper, granulated beef bouillon, and knead until everything is combined.
5
Fold white American cheese into 4 equal layers and sandwich it between two patties.
6
Form the patty into a disk.
7
Cook the patties in a cast iron skillet until a dark crust forms.
8
Flip the patties and cook for 3 more minutes.
9
Add a couple tbsp of water, cover, and steam to finish cooking.
10
Make a katsu sauce by combining ketchup, Worcestershire sauce, oyster sauce, sugar, and soy sauce.