Put the 60 grams onions in a microwave-safe bowl, cover the bowl and microwave at 800 watts for 4 minutes. You want them to be soft and just starting to brown. Leave the onions covered and let them cool enough to handle.
60 grams onions
In a separate bowl, add the 16 grams panko, 2 tablespoons milk, 2 teaspoons oyster sauce, and ¼ teaspoon black pepper and mix to combine.
16 grams panko, 2 tablespoons milk, 2 teaspoons oyster sauce, ¼ teaspoon black pepper
When the onions have cooled a bit, add them to the panko mixture along with the 225 grams ground beef, and knead together until it's well combined.
225 grams ground beef
Split the mixture in half and form them into 2 patties that are about a ¾-inch (2cm) thick.
Place them on a plate or tray and make an indentation in the center to keep them from puffing up.
Prepare the gravy mixture by stirring the ¾ cup low salt beef stock, 1 ½ tablespoons soy sauce, ½ teaspoon Worcestershire sauce, and 2 teaspoons potato starch together.
¾ cup low salt beef stock, 1 ½ tablespoons soy sauce, ½ teaspoon Worcestershire sauce, 2 teaspoons potato starch
Add the 2 teaspoons vegetable oil to a frying pan and heat over medium heat until hot. Break the 2 eggs into the pan and then turn the heat down to low. Let the eggs fry until the white is cooked through and the yolk is done to your liking. Transfer the eggs to plate and set aside.
2 teaspoons vegetable oil, 2 eggs
Add the hamburger patties to the pan you fried the eggs in and turn up the stove to medium high heat. Fry the patties until they have a brown crust on one side and are cooked about a third of the way through (about 2 ½ minutes). Flip the patties and fry until they're almost cooked through.
Transfer the patties to a plate and then add the 70 grams button mushrooms and 70 grams onions to the pan. Sauté until they are well browned and caramelized.
70 grams button mushrooms, 70 grams onions
Add the ½ tablespoon dark rum and deglaze the pan.
½ tablespoon dark rum
Add the beef stock mixture and return the hamburger patties to the pan. Turn up the heat and boil the gravy until it has thickened, turning the patties over to glaze them evenly.
Finish the gravy by adding the 1 tablespoon cream and stirring to combine evenly.
1 tablespoon cream
To plate the Loco Moco, put down a mound of hot cooked rice. Top with a beef patty, and then cover everything with gravy. Garnish your Loco Moco with fried shallots or onions, and then place an egg on top.
cooked rice, fried shallots or onions