Gather all the ingredients. For the cooked rice, please note that 1½ US measuring cups of uncooked Japanese short-grain white rice are 2 rice cooker cups (300 g, 10.6 oz) of uncooked rice and yield roughly 4 servings (3½ cups, 660 g, 23.2 oz) of cooked rice. See how to cook short-grain rice with a rice cooker, a pot over the stove, an Instant Pot, or a donabe.

Chop 1 onion finely.

Heat 1 Tbsp extra virgin olive oil in a large pan on medium-high heat and sauté the onion until translucent.

Turn off the heat and divide the sautéed onion in half (half for the gravy and half for the patty).

Cut 6 button mushrooms into thin slices. Heat ½ Tbsp extra virgin olive oil in a small saucepan on medium heat and sauté the mushrooms until soft. Add half of the sautéed onion and stir together.

Add 1½ cups beef stock/broth, 1 tsp Worcestershire sauce, and 1 tsp soy sauce.

Skim any foam or scum on the surface. Season with Diamond Crystal kosher salt and ⅛ tsp freshly ground black pepper.

In a small bowl, combine 1 Tbsp potato starch or cornstarch and 1 Tbsp water and whisk well to mix together. Pour the potato starch mixture into the gravy and thoroughly mix together. Simmer until the gravy is a bit thicker. Turn off the heat and set aside.

In a large bowl, add ¾ lb ground pork/beef and the rest of the sautéed onion. Add ⅓ cup panko (Japanese breadcrumbs), 1 large egg (50 g each w/o shell), 2 Tbsp milk, 1 tsp Worcestershire sauce, ½ tsp nutmeg, 1 tsp Diamond Crystal kosher salt, and ⅛ tsp freshly ground black pepper.

Mix the meat well until the mixture gets sticky and pale, and then divide into 4.

Make 4 large patties (or 6 medium patties, if you prefer). Toss each portion of mixture from one hand to the other hand repeatedly about 5 times in order to release air inside the mixture. If you don’t release the air inside, the meat patties will crack. After tossing, make oval-shaped patties. The top should be slightly round and not flat. Keep the patties in the fridge for at least 30 minutes before cooking so that the meat combines together.

In a large pan, heat ½ Tbsp extra virgin olive oil over medium heat and place the patties gently on the pan. (If you‘re doubling the recipe, fry in batches.) Indent the center of each patty with 2 fingers because the center of patties will rise with the heat. Cook the patties for about 5 minutes. Do not flip until the bottom of the patties is nicely browned. Cover and cook for 5 minutes to thoroughly cook the inside of the patties (adjust cooking time depending on patty’s thickness). At this time, you can also reheat the gravy and make the fried eggs with 4 large eggs (50 g each w/o shell) and ½ Tbsp extra virgin olive oil.

Serve 4 servings cooked Japanese short-grain rice on individual plates. Transfer the patties to the plates, pour the gravy, and top each with a fried egg. Chop 1 sprig parsley and sprinkle on top for garnish. Serve immediately.

You can keep the leftovers in an airtight container and store in the refrigerator for 3 days or in the freezer for a month.