1Finely chop the onion. Heat 5 grams of vegetable oil in a pan over medium heat, add the chopped onion, and sauté until translucent and softened, about 5-7 minutes. Remove from heat and let cool completely.
3In a large mixing bowl, combine the ground beef, ground pork, cooled sautéed onion, the panko and milk mixture, egg, salt, black pepper, and nutmeg. Mix thoroughly with your hands until all ingredients are well combined and the mixture becomes slightly sticky. Do not overmix.